Effect of flooding-drawdown cycle on vegetation in a system of floating peat mat and pond

The relationship between vegetation and seasonal changes in water level was examined in a system of terrestrializing floating peat mat and pond in a warm temperate zone. The duration of flooding, or drawdown period, is related to vegetation in the mat. The first process of terrestrialization would be the attenuation of floating-sinking movement of the mat and the consequent stabilization of water level. Water level at the time when the movement of the mat was attenuated determined the subsequent vegetation change at the site. Two series of succession according to terrestrialization were recognized, and started from initial conditions of low and high water levels respectively. Habitats in low initial water levels experienced short flooding and long drawdown periods. Species changes in the successional series were:Menyanthes trifoliata-Rhynchospora fauriei-Eriocaulon sikokianum-Sphagnum cuspidatum. Submerged peat was experimentally emerged, and the crowded community ofRhynchospora fauriei andEriocaulon sikokianum established within one or two years. Appearance of these species was controlled by the water level of the habitats in winter. Another series of species changes in terrestrialization process was:Menyanthes trifoliata-Phragmites australis-Carex thunbergii orIsachne globosa. Habitats of these types of vegetation were in the area with relatively high initial water level (long flooding and short drawdown) when the floating-sinking movement of the mat attenuated. After the temporal paludification, the water level was lowered by the accumulation of peat in the process of terrestrialization.     

Organoselenium-mediated addition of carbon radicals to 4',5'-unsaturated uracil-nucleosides and its stereocontrol

Stereocontrolled addition of carbon radicals to 4',5'-unsaturated uracil-nucleosides can be accomplished by using organoselenium reagents as a radical source. This provides a new method for C-C bond formation at the 5'-position.     

The contribution of aromatic components in Katsuobushi to preference formation and reinforcement effect

Katsuodashi, a dried bonito broth, is very basic and indispensable in Japanese cuisine and contains taste-exhibiting components and unique aroma. We previously reported that its unique aroma contributes to the preference and reinforcement effect associated with dried bonito. This study aims to elucidate the contribution of aromatic components in Katsuobushi to preference formation and reinforcement effect. Volatile components obtained from dried bonito were fractionated and the fractions were subjected to two-bottle choice test. The fractionation test suggested that the component responsible for the preference is not one but comprises multiple components. In the GC–MS analysis/reconstruction test, solution with aromatic flavor narrowed down to 125 compounds had preference, and also had reinforcement effect. Moreover, GC–MS–olfactometry analysis narrowed down the candidate components to 28 out of 125. Mice showed preference for the test solution with aromatic flavor reconstructed with 28 components but did not show reinforcement behavior.     

Synthesis of 3'alpha-carbo-substituted 2',3'-dideoxyribonucleosides from naturally occurring nucleosides.

Naturally occurring ribonucleosides, uridine and adenosine, were converted to their 3'alpha-CH2CO2Me and 3'alpha-CH2PO(OPh)2 2',3'-dideoxy analogues. The present reaction sequence starts with oxidative cleavage of the 2',3'-cis-diol system, and involves radical-mediated reconstruction of furanose ring as the key step.     

Transient thyrotoxicosis after unilateral adrenalectomy in two patients with Cushing's syndrome

We found transient hyperthyroidism in the course of hydrocortisone withdrawal in two patients who had undergone unilateral adrenalectomy to resect cortisol-hypersecreting adenoma. A 38-yr-old woman showed clinical thyrotoxicosis 3 months after the operation. Serum T4, T3 and TBG levels were 11.9 micrograms/dl, 310 ng/dl and 16.5 micrograms/ml, respectively. She was given methimazole (MMI) 15 mg/day for 4 weeks. After the cessation of MMI treatment, she eventually recovered to the euthyroid state. The other patient, a 34-yr-old man showed very mild clinical symptoms of hyperthyroidism 2 months after the operation. Serum T4, T3 and TBG levels were 10.4 micrograms/dl, 240 ng/dl and 14.5 micrograms/ml, respectively. In this case, no antithyroid drug was given. Two to three months after the onset of hyperthyroidism, he returned to the euthyroid state spontaneously. We carefully eliminated the possibility of factitious thyrotoxicosis in both cases. They had neither neck pain nor fever. Both had low radioactive iodine uptake by the thyroid. Therefore, we diagnosed them as painless thyroiditis induced after the resection of hypersecreting adrenal adenoma.     

Seasonal change in the redox property of peat and its relation to vegetation in a system of floating mat and pond

A relationship was sought between species distribution and seasonal change in the redox property of peat in a floating mat in Mizorogaike Pond, central Japan. The mat surface experienced an annual submergence-emergence cycle due to its sinking-rising movement. Redox potential (Eh) of the surface peat showed little difference between communities in the mat in the submergence season (January–June) and early emergence season (July–August). However variation in Eh among communities was clear in the late emergence season (September–December). Among seven communities in the floating mat, theMenyanthes trifoliata-Rhynchospora fauriei, M. trifoliata-Eriocaulon sikokianum-E. bondoense f.pilosum, Sphagnum cuspidatum andM. trifoliata-Carex thunbergii communities had high Eh (400–600 mV) in the late emergence season, while theMenyanthes trifoliata andPhragmites australis-M. trifoliata communities had lower Eh (200–400 mV). TheM. trifoliata-Isachné globosa community was intermediate (300–500 mV). The earlier the emergence of the peat surface began, the higher the Eh became in the late emergence season.