Studies on interrelationship of various ions in absorption by tobacco plants (Part 1) relation of nitrogen forms and cation levels in culture solution

The nutrient absorption by tobacco plants is sensitve to the condition of culture media, as a close absorbing relationship is kept among various nutrient elements. Tobacco plant, comparing with other plants, contains inorganic bases in its tissue in especially large amounts as against other inorganic elements. The reciprocal proportion of various bases has a great influence upon the growth and the quality of the leaf.     

Translocation of serine from leaves to roots in tobacco plants

It has been reported that nitrogen in the leaves of tobacco plant was translocated to the stem and root during the ripening period (1). Free amino acids in the leaves would play an important role in the translocation of nitrogen. It was also reported that the amino acids injected into the tobacco leaves were translocated to the roots (2,3). It seems probable that the translocation of amino acids would be characteristic among the individual amino acid. As reported previously, ¹⁴C assimilated in the leaves is translocated rapidly to the roots (2). Although it has been well known that the photosynthetic product was translocated mainly in the form of sugar, possibility that a part of photosynthetic products is translocated in the form of amino acid would be expected, because the carbon is incorporated rapidly into some of the amino acids, such as glycine, serine and alanine (4).     

Mineral composition of leaves and bark in aluminum accumulators in a tropical rain forest in Indonesia

Mineral composition including AI, Ca, Mg, P, S, and Si and relationships between Al and other elements such as Ca, Mg, P, S, and Si in leaves and bark of trees in a tropical rain forest in West Sumatra were studied. Sixty five tree species and 12 unidentified trees were referred to as AI accumulators based on Chenery\s's definition (more than 1 g kg^-1 Al in leaves). For most of the Al accumulators, Al concentration in leaves was higher than in bark. However, some members of Euphorbiaceae, Melastomataceae, and Ulmaceae families showed a reverse trend. Most of the non-accumulators also showed a higher Al concentration in bark than in leaves. These results indicated that there was a difference in the mechanism of Al accumulation in tree bodies. Some of the Al accumulators showed an extremely high Al concentration (more than 10 g kg^-1) not only in the mature leaves, but also in the new leaves. Analysis of the relationships between the concentration of Al and the other 5 elements in leaves, revealed that Al accumulators could be separated into two groups at the Al concentration of 3 g kg^-1. This finding suggested that new criteria based on Al concentration (23 g kg^-1) or Al/Ca ratio in leaves could be proposed in order to define Al accumulators, apart from Chenery's criterion. Aluminium accumulators with an Al concentration in leaves lower than 3 g kg^-1 (AI accumulators <3 g kg^-1) showed the same trend as the non-accumulators in terms of these elemental relationships, while Al accumulators with an Al concentration in leaves higher than 3 g kg^-1 (AI accumulators 23 g kg^-1) showed a different trend from the non-accumulators. The Al accumulators 23 g kg^-1 and the other trees (AI accumulators < 3 g kg^-1 and non-accumulators) showed separately positive correlations between the concentrations of AI and Ca (or Mg) in the leaves. This observation seems to be opposite to general findings in plant nutrition, i.e. inhibition of Ca or Mg uptake by AI. A positive correlation between Al and S was also observed for all the trees. The Al accumulators ≥3 g kg^-1 showed positive correlations between the concentrations of Al and P (or Si) in the leaves, unlike the other trees. These findings suggested that Al stimulated P, S, or Si accumulation in leaves or Al was transported with P, S, or Si for the Al accumulators ≥3 g kg^-1. No negative relationships between Al and the other 5 elements in the leaves were observed for the Al accumulators ≥3 g kg^-1.     

A histone acetyltransferase regulates active DNA demethylation in Arabidopsis

Active DNA demethylation is an important part of epigenetic regulation in plants and animals. How active DNA demethylation is regulated and its relationship with histone modification patterns are unclear. Here, we report the discovery of IDM1, a regulator of DNA demethylation in Arabidopsis. IDM1 is required for preventing DNA hypermethylation of highly homologous multicopy genes and other repetitive sequences that are normally targeted for active DNA demethylation by Repressor of Silencing 1 and related 5-methylcytosine DNA glycosylases. IDM1 binds methylated DNA at chromatin sites lacking histone H3K4 di- or trimethylation and acetylates H3 to create a chromatin environment permissible for 5-methylcytosine DNA glycosylases to function. Our study reveals how some genes are indicated by multiple epigenetic marks for active DNA demethylation and protection from silencing.     

Bioactive Alkaloids from the Sea: A Review

In our ongoing search for bioactive substances from marine organisms, novel alkaloids have been isolated. Pinnatoxins and pinnamine, potent shellfish poisons, were purified from the Okinawan bivalve Pinna muricata. Pinnatoxins activate Ca²⁺ channels. Halichlorine was isolated from the marine sponge Halichondria okadai. This compound inhibits the induction of VCAM-1. Drugs that block VCAM-1 may be useful for treating coronary artery diseases, angina, and noncardiovascular inflammatory diseases. Pinnaic acids, which are cPLA₂ inhibitors, were also obtained from P. muricata. Interestingly, the structures of pinnaic acids are closely related to that of halichlorine. Norzoanthamine hydrochloride, isolated from the colonial zoanthid Zoanthus sp., suppresses decreases in bone weight and strength in ovariectomized mice, and could be a good candidate for an osteoporotic drug. Ircinamine, purified from the marine sponge Ircinia sp., has a reactive thioester. Aburatubolactams, inhibitors of superoxide anion generation, were isolated from Streptomyces sp. This article covers the bioactive marine alkaloids that have been recently isolated by this research group.     

Effects of treatment with polysulfated glycosaminoglycan on serum cartilage oligomeric matrix protein and C-reactive protein concentrations, serum matrix metalloproteinase-2 and -9 activities, and lameness in dogs with osteoarthritis

OBJECTIVE: To investigate the effects of polysulfated glycosaminoglycan (PSGAG) treatment on serum cartilage oligomeric matrix protein (COMP) concentration, matrix metal-loproteinase-2 (MMP-2) and -9 (MMP-9) activities, C-reactive protein (CRP) concentration, and lameness scores in dogs with osteoarthritis. ANIMALS: 16 dogs with osteoarthritis and 5 clinically normal dogs. PROCEDURES: Dogs with osteoarthritis had a history of chronic lameness, and osteophytes were observed on radiographic evaluation of the affected joint. Polysulfated glycosaminoglycan was administered IM twice a week for a total of 8 treatments to all dogs with osteoarthritis and to clinically normal control dogs. RESULTS: Lameness scores after PSGAG treatment in osteoarthritic dogs improved in 12 of the 16 dogs. Serum COMP concentrations in osteoarthritic dogs were significantly higher than in control dogs before treatment. Lameness scores in osteoarthritic dogs decreased significantly after treatment, compared with before treatment. Lameness scores of 9 dogs with hind limb lameness improved significantly after treatment; these dogs had corresponding decreases in serum COMP concentrations. After treatment, serum COMP concentrations and lameness scores of 7 dogs with forelimb lameness remained high and were significantly higher than those of dogs with hind limb lameness. Serum MMP-9 activities of dogs with forelimb lameness were significantly higher than in dogs with hind limb lameness after treatment. CONCLUSIONS AND CLINICAL RELEVANCE: IM administration of PSGAG inhibited COMP degradation in dogs with osteoarthritis. Results indicate that decreases in serum COMP concentrations might be related to improvement in lameness after PSGAG treatment.     

Studies on inter-relationship of various ions in absorption by tobacco plants IV

The foliar symptoms of magnesium deficiency occur not only by the decrease in the contents of exchangeable magnesium in soil, but the antagonistic interaction among the nutrient elements in absorption. The relationship between phosphorus and magnesium in absorption was reported previously (1). In this paper influence of potassium and calcium on the magnesium absorption of tobacco plant was investigated.     

Effect of two whole-crop rice (Oryza sativa L.) cultivars on methane emission and Cu and Zn uptake in a paddy field fertilized with biogas slurry

A field experiment was carried out to evaluate the effect of two whole-crop rice (Oryza sativa L.) cultivars, TULT and Takanari, on methane (CH₄) emission in a paddy field fertilized with biogas slurry (BS) at rates of 0 (NF), 100 (BS100) and 300 (BS300) kg nitrogen (N) ha^?1, in comparison with chemical fertilizer CF100 (100 kg N ha^?1). Takanari produced significantly higher biomass (P < 0.001) than TULT and showed significantly (P < 0.01) lower CH₄ emission than TULT. BS applications caused higher CH₄ emission (52 ± 27 and 80 ± 19 g m^?2 in BS100 and BS300, respectively) than did CF100 (42 ± 18 g m^?2) and NF (28 ± 10 g m^?2) in TULT. In contrast, there was no significant difference in CH₄ emission in Takanari among the treatments (26 ± 2, 26 ± 2, 32 ± 4, 29 ± 8 g m^?2 in NF, CF100, BS100 and BS300, respectively). Methane oxidizing bacteria (MOB) showed significantly (P < 0.05) higher populations in Takanari than in TULT at harvest, which might be due to the higher root biomass (10.3 ± 2.2 g hill^?1) in Takanari than in TULT (8.9 ± 1.8 g hill^?1). MOB was significantly correlated with tiller number (R² = 0.176*) and plant biomass (R² = 0.242*). BS application showed higher copper (Cu) uptake in Takanari while it was not high in TULT. In contrast, it showed no difference in zinc (Zn) uptake in both varieties. Uptake of Cu was not different between the two varieties, while uptake of Zn in the grain was higher in TULT than in Takanari. The present study suggests that CH₄ emission deriving from BS application in paddy field can be mitigated by selecting an appropriate cultivar, like Takanari. However, care should be taken for heavy metal uptake in selecting cultivars.