Effects of snow-load and shading by vascular plants on the vertical growth of hummocks formed by Sphagnum papillosum in a mire of northern Japan

The growth of hummock Sphagnum species in bogs depends on hydrological and climatic conditions, with different hummock morphologies being found across geographical regions. We investigated how plant shade and winter snow-load regulate the growth pattern and height of Sphagnum papillosum hummocks in a cool-temperate bog in Japan. Hummocks were subjected to four treatments across 2?years (1 hummock per treatment per year): no treatment (control), snow-load-free (S), vascular plant trimming (T), and snow-load-free and vascular plant trimming in combination (S&T). Further, the effects of vascular plant cover and snow -load on the vertical growth and height of hummocks were examined. Annual growth rates of S. papillosum were higher for the control (34?C41?mm) than S&T treatment, and were intermediate for separate S and T treatments. In contrast to vascular plant-growing hummocks, vascular plant-trimmed hummocks showed a negative correlation between water-table depth (measured from the capitulum to the water-table) and Sphagnum growth. Hence, in summer, shading by vascular plants may prevent desiccation and facilitate the growth of Sphagnum. Snow-loaded hummocks were weighed down by 3?C11?cm. After snowmelt, the shoots continued to grow within the water-table depth range that allowed growth. Hence, heavy winter snow-loads may depress the surfaces of hummocks closer to the water-table, which stimulates Sphagnum growth, resulting in the recovery of hummock height. Thus, the water stress caused by summer desiccation is critical in regulating the upper limit of hummock height in bogs subject to dry summer conditions and heavy winter snowfall.     

Effect of External pH on the Cytoplasmic and Vacuolar pHs in Mung Bean Root-Tip Cells: A 31P Nuclear Magnetic Resonance Study

The effect of the external pH on the intracellular pH in mungbean (Vigna mungo (L.) Hepper) root-tip cells was investigatedwith the ³¹P nuclear magnetic resonance (NMR) method. The ³¹PNMR spectra showed three peaks caused by cytoplasmic G-6-P,cytoplasmic P_i and vacuolar P_i. The cytoplasmic and vacuolarpHs could be determined by comparing the P_i chemical shiftswith the titration curve. When the external pH was changed overa range from pH 3 to 10, the cytoplasmic pH showed smaller changesthan the vacuolar pH, suggesting that the former is regulatedmore strictly than the latter. The H⁺-ATPase inhibitor, DCCD,caused the breakdown of the mechanism that regulates the intracellularpH. H⁺-ATPase appears to have an important part in the regulationof the intracellular pH. (Received January 4, 1984; Accepted August 27, 1984)     

Electrophoretic analysis of soluble proteins specifically synthesized under phosphate deficiency in the mycelia ofPholiota nameko

Mycelial soluble proteins ofPholiota nameko labeled in vivo during the Pi-supplied (P⁺) and the Pi-depleted (P⁻) cultures were separated by SDS-polyacrylamide gel electrophoresis and two-dimensional polyacrylamide gel electrophoresis, and visualized by fluorography. A comparison of protein profiles from the P⁺ and P⁻ cultures showed that Pi deficiency induces the synthesis of 15 polypeptides and an increase in the relative amount of 29 polypeptides. These result suggests that many proteins may be specifically synthesized de novo under Pi deficiency as part of the adaptive mechanism for this condition.     

Studies on the relations of selenium and Keshan disease

Keshan disease is an endemic cardiomyopathy of unknown cause in The People’s Republic of China that occurs most frequently in children under 15 years of age and women of child-bearing age. Studies of children 1–9 years old in Mianing County of Sichuan Province have indicated that Keshan disease is a selenium responsive condition. Incidence rates of 9.5–13.5/1000 in 1974–1975 were reduced to 1–2/1000 in children treated with a tablet weekly of 0.5–1 mg sodium selenite. During 1974–1977, only 21 cases of the disease occurred in 36,603 treated children, compared with 106 cases in 9430 untreated children, of whom 53 died and 5 still have insufficient heart function. Occurrence of the disease was invariably associated with a lower selenium content of cereals, and of hair (less than 0.12 ppm Se) in residents from affected, compared with non-affected, areas. The dose relationship between selenium and regional characteristics of Keshan disease suggests that it is probably a biogeochemical disease; other etiological factors have also been considered.