Classification and Phytogeography of Larch Forests of Northeast Asia

This study focuses on a phytosociological system of the extensive Larix gmelinii and Larix cajanderi dominated forests and woodlands that span the nemoral, boreal and subarctic zones in northeast Asia in the Russian Far East, Eastern Siberia and northern China, an area that covers more than 5 million km². A total of 299 relevés representing different parts of the larch forest range were used to classify communities in this area into the boreal Rhytidio rugosi-Laricetea sibiricae and Vaccinio-Piceetea and to the nemoral Querco mongolicae-Betuletea davuricae. The hierarchical system of lower syntaxa of larch forests and woodlands of northeast Asia includes 24 associations and nine subassociations. Nineteen associations and two alliances – Rhododendro aurei-Laricion cajanderi and Rhododendro daurici-Laricion gmelinii – are described for the first time. Two associations were classified into Dictamno dasycarpi-Quercion mongolicae of Lespedezo bicoloris-Quercetalia mongolicae representing the nemoral class Querco mongolicae-Betuletea davuricae. All larch communities in the nemoral zone represent different post-fire-event stages. Eleven associations occurring in humid conditions of the boreal zone and in the areas influenced by the Pacific Ocean are classified into Abieti nephrolepidis-Piceion jezoensis, Piceion jezoensis and Pino pumilae-Piceion jezoensis representing boreal forests of humid maritime regions belonging to the order Abieti veitchii-Piceetalia jezoensis. In this area seral larch communities occupy zonal sites, and primeval larch forests may occur only in edaphic conditions restricting the distribution of zonal dominants, Picea jezoensis and the species of Abies. The area of continuous permafrost within the boreal zone having continental and ultracontinental climate conditions is occupied by primeval larch forests united in Ledo palustris-Laricion cajanderi and Rhododendro aurei-Laricion cajanderi of Ledo palustris-Laricetalia cajanderi, and on sites with dry soils with a deeper frozen horizon in Lathyro humilis-Laricion cajanderi of Lathyro humilis-Laricetalia cajanderi.     

Physiological Structure of the Critical Photoperiod of Lemna paucicostata 6746

The critical day length or the length of the critical photoperiodfor the short-day duckweed, Lemna paucicostata 6746 is about14 h (Oota 1983). With the min-SD method, I found that not thewhole critical photoperiod but only its initial and terminalbrief fractions, called respectively the LI- and L2-phases,need be illuminated for a given day to be a noninductive day.Inversely, the darkened LI- and/or L2-phase makes the day inductive.The rest of the day can be either darkened or illuminated withoutmodifying the inductive or noninductive property of the day. Thus, the physiological structure of the critical photoperiodfor L. paucicostata 6746 closely resembles that of the criticalphotoperiod for the long-day duckweed, L. gibba G3 (Oota 1981). (Received May 24, 1983; Accepted September 21, 1983)     

Distribution of Fallover in the Carboxylase Reaction and Fallover-Inducible Sites among Ribulose 1,5-Bisphosphate Carboxylase/Oxygenases of Photosynthetic Organisms

The biphasic reaction course, fallover, of carboxyla-tion catalysedby ribulose 1,5-bisphosphate carboxylase/ox-ygenase (RuBisCO)has been known as a characteristic of the enzyme from higherland plants. Fallover consists of hysteresis in the reactionseen during the initial several minutes and a very slow suicideinhibition by inhibitors formed from the substrate ribulose-l,5-bisphosphate(RuBP). This study examined the relationship between occurrenceof fallover and non-catalytic RuBP-binding sites, and the putativehysteresis-inducible sites (Lys-21 and Lys-30S of the largesubunit in spinach RuBisCO) amongst RuBisCOs of a wide varietyof photosynthetic organisms. Fallover could be detected by followingthe course of the carboxylase reaction at 1 mM RuBP and thenon-catalytic binding sites by alleviation of fallover at 5mM RuBP. RuBisCO from Euglena gracilis showed the same linearreaction course at both RuBP concentrations, indicating an associationbetween an absence of fallover and an absence of the non-catalyticbinding sites. This was supported by the results of an equilibriumbinding assay for this enzyme with a transition state analogue.Green macroalgae and non-green algae contained the plant-type,fallover enzyme. RuBisCOs from Conjugatae, Closterium ehrenbergii,Gona-tozygon monotaenium and Netrium digitus, showed a muchsmaller decrease in activity at 1 mM RuBP than the spinach enzymeand the reaction courses of these enzymes at 5 mM RuBP werealmost linear. RuBisCO of a primitive type Conjugatae, Mesotaeniumcaldariorum, showed the same linear course at both RuBP concentrations.Sequencing of rbcL of these organisms indicated that Lys-305was changed into arginine with Lys-21 conserved. ⁷ On leave from Research and Development Center, Unitika Ltd.,23 Kozakura, Uji, Kyoto, 611 Japan. ⁸ Present address: Department of Applied Biological Chemistry,Faculty of Agriculture, Tohoku University, Tsutsumidori-Ama-miyamachi, Sendai, 981 Japan. ⁹ Present address: National Institute for Basic Biology, Myodaiji,Okazaki, 444 Japan. ¹⁰ Present address: Department of Environmental Biology, TokyoPharmaceutical University, Hachioji, Tokyo, 192-03 Japan.     

Impairment of Blood-Cerebrospinal Fluid Barrier in Multiple Sclerosis

The blood-CSF barrier (BCB) function in active multiple sclerosis (MS) was studied by means of CSF proteins analysis using disc electrophoresis and immunofixation. Forty-five CSF samples were obtained by repeat lumbar punctures at various intervals, from four autopsy-proven cases and three male and nine female patients with clinically definite MS. When total protein content was increased, the percentages of prealbumin and tau fraction were decreased significantly in association with the presence of haptoglobin (Hp) polymers in nearly all the samples, as a result of increased permeability of the BCB. Even when the total protein content was normal, Hp polymers were detected in 56% of the samples, and the tau fraction tended to be decreased. Monoclonal immunoglobulin and Hp polymers were both recognized in some cases. The results suggested a more frequent occurrence of BCB impairment in MS than had formerly been revealed by CSF albumin analysis, and accorded with the recent reports of contrast-enhancing lesions of MS brain in computerized tomography.     

α-1-Antichymotrypsin variant detected by PCR-single strand conformation polymorphism (PCR-SSCP) and direct sequencing

A new mutant -1-antichymotrypsin (variant ACT) was found by polymerase chain reaction single strand conformation polymorphism and direct sequencing. In this variant ACT, two bases (AA) were deleted from codon 391. This resulted in a different amino acid sequence downstream of the deletion point, elongating the peptide chain by 10 amino acids.     

Evidence against involvement of circadian floral rhythm in the critical daylength measurement in Lemna gibba G3

Using the min-LD method, light requirements of the L1- and L2-phasesof L. gibba G3 were found to be satisfied by only 5 min illuminationgiven respectively from CT 0:00 to 0:05 and from CT 11:55 to12:00. This rigorous time sense was displayed without any alterationeven in the presence of iron reagents, e.g., 10^–5 M o-phenanthroline,10^–5M,'-dipyridyl and 10–6 M kinetin, which completely eliminatedcircadian rhythmicity in reproductive (flower production) aswell as vegetative (frond production) response to a light pulsescanning a continuous dark period. Circadian rhythms of metabolicactivities, e.g., active K⁺ ion uptake and respiratory CO₂ output,were not changed at all by the iron reagents. These and relevantresults suggested that in this long-day duckweed, the circadianoscillator, probably located in the meristem and sensitive toiron deficiency, only modulates the frond and flower productionin the meristem and is not related to the critical daylengthmeasurement. (Received December 18, 1978; )     

Spectral dependence of the critical photoperiod in the long-day duckweed, Lemna gibba G3

Spectral dependence of the light sensitive L1- and L2-phasesof the critical photoperiod of Lemna gibba G3 was examined bythe min-LD method for wavelengths ranging from ca. 420 to 800nm. The L1-phase had a sharp peak of sensitivity at 650–680nm and a gentle slope of sensitivity ascending from 500 nm towardshorter wavelengths. The L2-phase showed remarkable sensitivityaround 750 nm and in the blue-violet regions (500 nm). Red/far-redphotoreversibility was confirmed for the LI-phase, but not forthe L2-phase. The properties of the light receptors involvedare discussed briefly. ¹Present address: National Institute for Basic Biology, Myodaiji,Okazaki 444, Japan. (Received May 14, 1979; )     

Enhancement of rat hepatic macrophages by treatment with interleukin-2 and streptococcal preparation OK432, with reference to antitumor activity,soluble factor production and Ia expression

Summary The effect of biological response modifiers, such as interleukin-2 (IL-2) and streptococcal preparation OK432, on the functions of hepatic macrophages was investigated. The macrophages, even with no exogenous stimulation, produced superoxide anion (O ₂ ^- ) and tumor necrosis factor (TNF), displayed cytotoxicity against K562 cells and cytostasis against P815 cells and expressed immune-region-associated antigen (Ia). IL-2 administered in vitro or in vivo enhanced O ₂ ^- production by hepatic macrophages and the intravenous injection of OK432 also enhanced O ₂ ^- production. Furthermore, IL-2 added to the culture medium of hepatic macrophages isolated from OK432-injected rats augmented O ₂ ^- production even more. The TNF production and Ia expression of the macrophages were also increased by the intravenous injection of OK432. As with O ₂ ^- production, the cytotoxicity of the cells was enhanced by OK432 injection or by IL-2 added to the culture medium and the combination of OK432 and IL-2 augmented their cytotoxicity even more. Thus, the present study suggested that IL-2 and OK432 induce the augmentation of the antitumor activity of hepatic macrophages, partly as a result of the increase in production of O ₂ ^- and TNF and Ia expression.