Tobacco Root Endophytic Arthrobacter Harbors Genomic Features Enabling the Catabolism of Host-Specific Plant Specialized Metabolites

Plant roots constitute the primary interface between plants and soilborne microorganisms and harbor microbial communities called the root microbiota. Recent studies have demonstrated a significant contribution of plant specialized metabolites (PSMs) to the assembly of root microbiota. However, the mechanistic and evolutionary details underlying the PSM-mediated microbiota assembly and its contribution to host specificity remain elusive. Here, we show that the bacterial genus Arthrobacter is predominant specifically in the tobacco endosphere and that its enrichment in the tobacco endosphere is partially mediated by a combination of two unrelated classes of tobacco-specific PSMs, santhopine and nicotine. We isolated and sequenced Arthrobacter strains from tobacco roots as well as soils treated with these PSMs and identified genomic features, including but not limited to genes for santhopine and nicotine catabolism, that are associated with the ability to colonize tobacco roots. Phylogenomic and comparative analyses suggest that these genes were gained in multiple independent acquisition events, each of which was possibly triggered by adaptation to particular soil environments. Taken together, our findings illustrate a cooperative role of a combination of PSMs in mediating plant species-specific root bacterial microbiota assembly and suggest that the observed interaction between tobacco and Arthrobacter may be a consequence of an ecological fitting process

Mechanism of Lipid Radical Formation Following Exposure of Epidermal Homogenate to Ultraviolet Light

It has been suggested that oxygen free radicals are important mediators of lipid peroxidation in the epidermis exposed to ultraviolet (UV) light. However, it is not clear whether it is the superoxide anion radical (O2-) or the hydroxyl radial (.OH) that plays the major role in producing the lipid radical (L.) following UV exposure. In this study, we used electron spin resonance (ESR) technique with the spin trap (5,5-dimethyl-1-pyrroline-N-oxide [DMPO]) to determine which active oxygen species is involved in the UV -induced lipid radical formation (DMPO-L.: aN = 15.5 G, aH = 22.7 G). In the presence of superoxide dismutase or the metal-chelating agent, the DMPO-spin adduct spectrum of lipid radicals was reduced remarkably. The lipid radicals were formed by the hydroxyl radical generation system, not the superoxide anion generation system. The hydroxyl radical was found to be the direct active oxygen species that can generate lipid radicals as a result of .OH-mediated hydrogen atom abstraction. Superoixde anion radical stimulated the generation of hydroxyl radical via the iron-catalyzed reaction

Involvement of Active Oxygen in Lipid Peroxide Radical Reaction of Epidermal Homogenate Following Ultraviolet Light Exposure

To elucidate the radical mechanism of lipid peroxidation induced by ultraviolet light (UV) irradiation, an electron spin resonance (ESR) study was made on epidermal homogenate prepared from albino rat skin. The exposure of the homogenate to UV light resulted in an increase in lipid peroxide content, which was proportional to the time of UV exposure. Using ESR spin trapping (dimethyl-1-pyrroline-N-oxide, DMPO), the DMPO spin adduct spectrum of lipid radicals (L·) was measured following UV exposure (DMPO- L· :aN = 15.5 G, aH ≈ 22.7 G), as was the spectrum of DMPO-hydroxyl radical (DMPO-OH, aN = aH = 15.5 G). In the presence of superoxide dismutase, the DMPO spin adduct spectrum of lipid radicals was found to be reduced remarkably. Therefore, it was shown that the generation of the lipid radicals partially involves superoxide anion radicals, in addition to hydroxyl radicals. In the ESR free-radical experiment, an ESR signal appeared at g = 2.0064 when the ESR tube filled with homogenate was exposed to UV light at-150°C. The temperature-dependent change in the ESR free radical signal of homogenate exposed to UV light was observed at temperatures varying from-150°C to room temperature. By using degassed samples, it was confirmed that oxygen is involved in the formation of the lipid peroxide radicals (LOO·) from the lipid radicals (L·)

Hyperspectral wavelength selection for estimating chlorophyll content of muskmelon leaves

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Effects of aphid honeydew sugars on the survival and fecundity of the aphidophagous gall midge Aphidoletes aphidimyza

Predatory gall midge Aphidoletes aphidimyza, which is used for augmentative biological control of aphids in greenhouses, take aphid honeydew as an energy source to survive. Currently Rhopalosiphum padi on barley plants and Melanaphis sacchari on sorghum plants are used as the banker plant systems for A. aphidimyza to control A. gossypii on eggplants in Japan. We analyzed the sugar components of three species aphid honeydew by HPLC. The major components of honeydew were sucrose, fructose and melezitose for A. gossypii, glucose and fructose for R. padi and glucose, fructose and melezitose for M sacchari. Two minor components for these three aphid species were maltose and trehalose. We investigated the influence of sugars including three aphid artificial honeydew, six sugar components of three species aphid honeydew and water on the longevity of unmated females and males of A. aphidimyza. Both females and males attained the longest lifespan on sucrose and artificial honeydew of A. gossypii. Mean longevities of both females and males were shortest when they were provided with only water. We conducted another experiment where a mated female was released in a cage with an eggplant seedling infested with A. gossypii and was fed with sucrose or only water. Number of eggs laid and survival of the female was examined every day. Females fed with sucrose lived significantly longer and laid more eggs in their lifetime than those with only water

Exploratory study of cold hypersensitivity in Japanese women: genetic associations and somatic symptom burden

Abstract Temperature perception is essential for humans to discern the environment and maintain homeostasis. However, some individuals experience cold hypersensitivity, characterized by a subjective feeling of coldness despite ambient environmental temperatures being normal, the underlying mechanisms of which are unknown. In this study, we aimed to investigate the relationship between subjective cold symptoms and somatic burden or single nucleotide polymorphisms to understand the causes of cold hypersensitivity. We conducted an online questionnaire survey [comprising 30 questions, including past medical history, subjective symptoms of cold hypersensitivity, and the Somatic Symptom Scale-8 (SSS-8)]. Respondents were 1200 Japanese adult female volunteers (age: 20–59 years), recruited between April 21 and May 25, 2022, who were customers of MYCODE, a personal genome service in Japan. Among the 1111 participants, 599 (54%) reported cold hypersensitivity. Higher cold hypersensitivity severity was positively associated with the SSS-8 scores. Additionally, a genome-wide association study for cold hypersensitivity was conducted using array-based genomic data obtained from genetic testing. We identified 11 lead variants showing suggestive associations (P < 1 × 10–5) with cold hypersensitivity, some of which showed a reasonable change in expression in specific tissues in the Genotype-Tissue Expression database. The study findings shed light on the underlying causes of cold hypersensitivity