Cheating根粒菌の生成機構と生態、及びそれに対する宿主マメ科植物の防御機構の解明

要約のみTohoku University佐藤修正課

Inhibitions of Growth and Lateral Branch Development by Calmodulin Antagonists in Hairy Roots of Lithospermum erythrorhizon, Atropa belladonna and Daucus carota

Hairy roots of Lithospermum erythrorhizon, belladonna and carrot, which were induced by inoculation with Agrobacterium rhizogenes harboring the Ri plasmid, were cultured on a medium containing 0.1, 1, 10, 30 or 100μM W-7 or W-5, calmodulin antagonists. Growth rates of L. erythrorhizon and belladonna hairy roots cultured on all media containing W-7 were lower than that of the roots cultured without W-7. Growth of carrot hairy roots was inhibited by W-7 above 30μM. Inhibition rates of the root growth by high concentrations of W-5 were lower than those of the growth by the same concentrations of W-7. In the case ofthe development of lateral roots on hairy roots, 30 and 100μM W-7 or W-5 inhibited formation of lateral roots. The number of lateral roots formed by culturing on a medium containing W-7 was lower than that of the roots formed on the medium containing W-5. These results strictly suggest that calmodulin acts upon the growth of hairy roots and the development of lateral roots on hairy roots

Dramatic Transcriptional Changes in an Intracellular Parasite Enable Host Switching between Plant and Insect

Phytoplasmas are bacterial plant pathogens that have devastating effects on the yields of crops and plants worldwide. They are intracellular parasites of both plants and insects, and are spread among plants by insects. How phytoplasmas can adapt to two diverse environments is of considerable interest; however, the mechanisms enabling the “host switching” between plant and insect hosts are poorly understood. Here, we report that phytoplasmas dramatically alter their gene expression in response to “host switching” between plant and insect. We performed a detailed characterization of the dramatic change that occurs in the gene expression profile of Candidatus Phytoplasma asteris OY-M strain (approximately 33% of the genes change) upon host switching between plant and insect. The phytoplasma may use transporters, secreted proteins, and metabolic enzymes in a host-specific manner. As phytoplasmas reside within the host cell, the proteins secreted from phytoplasmas are thought to play crucial roles in the interplay between phytoplasmas and host cells. Our microarray analysis revealed that the expression of the gene encoding the secreted protein PAM486 was highly upregulated in the plant host, which is also observed by immunohistochemical analysis, suggesting that this protein functions mainly when the phytoplasma grows in the plant host. Additionally, phytoplasma growth in planta was partially suppressed by an inhibitor of the MscL osmotic channel that is highly expressed in the plant host, suggesting that the osmotic channel might play an important role in survival in the plant host. These results also suggest that the elucidation of “host switching” mechanism may contribute to the development of novel pest controls

Analytical Chemistry of Impurities in Amino Acids Used as Nutrients: Recommendations for Regulatory Risk Management

Proteinogenic amino acids are natural nutrients ingested daily from standard foods. Commercially manufactured amino acids are added to a wide range of nutritional products, including dietary supplements and regular foods. Currently, the regulatory risk management of amino acids is conducted by means of setting daily maximum limits of intake. However, there have been no reported adverse effects of amino acid overdosing, while impurities in low-quality amino acids have been identified as causative agents in several health hazard events. This paper reviews the analytical chemistry of impurities in amino acids and highlights major variations in the purity of commercial products. Furthermore, it examines the international standards and global regulatory risk assessment of amino acids utilized in dietary supplements and foods, recommending (1) further research on analytical methods that can comprehensively separate impurities in amino acids, and (2) re-focusing on the regulatory risk management of amino acids to the analytical chemistry of impurities