Changes in endogenous hormone levels and redox status during enhanced adventitious rooting by rare earth element neodymium of Dendrobium densiflorum shoot cuttings

The effects of neodymium nitrate (Nd3 ) on the adventitious rooting of Dendrobium densiflorum shoot cuttings were studied. The addition of Nd3 (5 μmol/L) to culture medium significantly increased rooting frequency. Histological investigation showed that Nd3 did not change the process of root initiation. Nd3 did not influence total endogenous cytokinin levels, but significantly increased the level of en-dogenous indole-3-acetic acid (IAA) in the base of shoot cuttings. Compared to the control, the ratio of IAA/cytokinins was very high in the Nd3 treatment. These results suggested that the enhanced rooting frequency may be related to the increase in endogenous IAA level in Nd3 treatment. Analysis of enzyme activities showed that the enhanced accumulation of the endogenous IAA by Nd3 should not be attributed to inhibition of IAA decomposition by IAA oxidase or promotion of cytokinin decomposition by cytokinin oxidase. Besides, Nd3 increased the ratio of reduced glutathione (GSH) and oxidized glutathione (GSSG) in the process of adventitious rooting while the ratio of ascorbate (ASC) to dehydroascorbate (DHA) was not affected.     

施用稀土多元复合肥对减少蔬菜中硝酸盐积累的研究

随着单元素氮类化肥的大量施用，蔬菜中富集了大量的硝酸盐，对人体存在着潜在的危害性，是食物污染的主要来源之一。本文介绍了采用萘乙二胺盐酸法（水果、蔬菜及其制品中硝酸盐和亚硝酸盐含量测定国标法）测定施用稀土多元复合肥后蔬菜中硝酸盐含量的变化情况，进行了稀土多元复合肥在农业生产中有效地控制蔬菜中硝酸盐积累的探索。     

T cell interactions with extracellular matrix proteins in patients with thyroid-associated ophthalmopathy

The roles of auxin and cytokinin in cell cycle reactivation were studied during the first 48 h of culture of mesophyll protoplasts of Nicotiana tabacum. Using hormone delay and withdrawal studies we found that auxin was required by 0-4 h of culture, whereas cytokinin was not required until hour 10-12, which is 6-10 h before S phase. Cycloheximide blocks division, indicating that protein synthesis is required. In an effort to detect a molecular response to either hormone, we examined the expression of the cell cycle marker, cdc2. Cdc2 expression was detected by 12 h of culture, coincident with the timing of the cytokinin requirement and well before the entry into S. However, cdc2 was partially induced by either auxin or cytokinin alone, suggesting that cdc2 expression is not the primary target of either hormone. Our hormone delay experiments suggest that there are separate signal transduction pathways leading from auxin and from cytokinin to reactivation of the cell cycle and that these pathways converge before S. The underlying mechanisms for these distinct pathways remain to be elucidated. Key Words. Auxin-Cytokinin-Tobacco-Protoplast-Development-cdc2     

Acetate Limitation and Nitrite Accumulation during Denitrification

Nitrite accumulated in denitrifying activated sludge mixed liquor when the carbon and electron source, acetate, was limited. If acetate was added to obtain a carbon-to-nitrogen (C:N) ratio in the range of 2:1 to 3:1, nitrate was completely consumed at the same rate with no nitrite accumulation, indicating that nitrate concentration controlled the respiration rate as long as sufficient substrate was present. However, when acetate was reduced to a C:N ratio of 1:1, while nitrate continued to be consumed, >50% of the initial nitrate-nitrogen accumulated as nitrite and 29% persisted as nitrite throughout an endogenous denitrification period of 8–9 h. While nitrite accumulated during acetate-limited denitrification, the specific nitrate reduction rate increased significantly compared with the rate when excess acetate was provided as follows: 0.034 mg-NO3-N∕mg-mixed liquid volatile suspended solids∕h versus 0.023 mg-NO3-N∕mg-mixed liquid volatile suspended solids∕h, respectively. This may be explained by nitrate respiration out-competing nitrite respiration for limited acetate electrons. Complete restoration of balanced denitrification and elimination of nitrite accumulation during denitrification required several weeks after the C:N ratio was increased back to 2:1.     

Changes in endogenous hormone levels and redox status during enhanced adventitious rooting by rare earth element neodymium of Dendrobium densiflorum shoot cuttings

The effects of neodymium nitrate （Nd^3＋） on the adventitious rooting of Dendrobium densiflorum shoot cuttings were studied. The addition of Nd^3＋ （5 μmol/L） to culture medium significantly increased rooting frequency. Histological investigation showed that Nd^3＋ did not change the process of root initiation. Nd^3＋ did not influence total endogenous cytokinin levels, but significantly increased the level of endogenous indole-3-acetic acid （IAA） in the base of shoot cuttings. Compared to the control, the ratio of IAA/cytokinins was very high in the Nd^3＋ treatment. These results suggested that the enhanced rooting frequency may be related to the increase in endogenous IAA level in Nd^3＋ treatment. Analysis of enzyme activities showed that the enhanced accumulation of the endogenous IAA by Nd^3＋ should not be attributed to inhibition of IAA decomposition by IAA oxidase or promotion of cytokinin decomposition by cytokinin oxidase. Besides, Nd^3＋ increased the ratio of reduced glutathione （GSH） and oxidized glutathione （GSSG） in the process of adventitious rooting while the ratio of ascorbate （ASC） to dehydroascorbate （DHA） was not affected.     

Prescribed medication and nutrition of social care patients in Crete, Greece

A Tn917 mutant of Staphylococcus carnosus TM300, nrIII, was isolated and characterized. Mutant nrIII did not take up nitrate or accumulate nitrite when grown in B-medium supplemented with up to 10 mM nitrate under anoxic conditions; however, it displayed wild-type levels of benzyl Delta viologen-linked nitrate reductase activity. Cultivated in B-medium with nitrate under oxic conditions, mutant nrIII accumulated fivefold less nitrite than the wild-type. The mutation in S. carnosus nrIII could be complemented with a 2-kb chromosomal EcoRI-HpaI fragment from the wild-type. The gene affected by transposon insertion in mutant nrIII was cloned and sequenced. Analysis of the deduced amino acid sequence revealed that this gene, designated narT, encodes a highly hydrophobic 42-kDa transmembrane protein of 388 amino acids and shows similarities to transport proteins that play a role in nitrate import or nitrite export. The inability of nrIII to take up nitrate under anoxic conditions and its ability to take up and accumulate nitrite in the presence of benzyl viologen, a nitrate ionophore, under the same conditions suggest that NarT represents a transport protein required for nitrate uptake under anoxic conditions in S. carnosus.