SPECTRAL CHANGE OF LIGHT WITH DEPTH IN SOME LAKES AND ITS SIGNIFICANCE TO THE PHOTOSYNTHESIS OF PHYTOPLANKTON

1. A linear relation was found between the relative light intensityat 5 in depth and the mean chlorophyll a content of the euphoticzone, when they were plotted on logarithmic scales. The intensitiesof underwater lights of different wave lengths were measuredby a photocell with various colored filters. It was recognizedthat with the increase in chlorophyll a content the proportionof blue light fraction became reduced and that of red lightincreased. A similar relation was also found in the sea.
2. Thephotosynthetic rate.light relation was investigated withthesuspension of cultured Chlorella and Tabellaria. At lowlightintensities, the photosynthetic rate for red light waslargerthan those for blue and green lights. The photosyntheticrateunder the mixed light of red and blue was equal to thesum ofthe rates in the individual lights, so far as the intensityof each light was low. But when the intensity of red light wassufficiently high, the addition of blue light brought no furtherincrease in photosynthesis.
3. The photosynthetic rate-depthrelations were investigated bythe surface and underwater exposuremethods. Good agreementswere found between the results obtainedby these two differentmethods. However, there are some discrepanciesbetween the resultsof in situ exposure experiments and thoseobtained by the twomethods.

(Received January 11, 1963; )     

EFFECTS OF PHYTOCHROME AND BLUE-NEAR ULTRAVIOLET LIGHT-ABSORBING PIGMENT ON DURATION OF COMPONENT PHASES OF THE CELL CYCLE IN ADIANTUM GAMETOPHYTES

Single-celled protonemata of the fern Adiantum capillus-veneris, kept under continuous red light, grew with a very low rate of cell division, and the cell cycle was arrested in the early G₁ phase. Cell division was induced by transferring the protonemata to the dark after various light treatments, and the duration of component phases in the cell cycle was determined by a continuous-labelling technique with 3H-thymidine. Blue light irradiation greatly reduced the duration of the G₁ phase but did not affect that of other phases. The greater the fluence of blue light, the shorter was the duration of G₁ phase was observed. In contrast, a brief exposure of red-light-grown protonemata to far-red light given immediately before the dark incubation showed no effect on the duration of G₁ S and M phases but significantly extended that of the G₂ phase. The effect of far-red light on the G₂ phase was reversed by red light, and the effects of red and far-red light were repeatedly reversible. The progression in the M phase was shown by means of a time-lapse video system to be not at all influenced by any pre-irradiation described above.     

Fourteen polymorphic microsatellite loci in the field gudgeon,Gnathopogon elongatus elongatus

We isolated and characterized 14 polymorphic microsatellite loci for the field gudgeon, Gnathopogon elongatus elongatus, a popular freshwater species in streams including agricultural canals in Japan. The number of observed alleles for each locus ranged from 9 to 24, and the values of observed and expected heterozygosities ranged from 0.750 to 1.000 and from 0.832 to 0.953, respectively. These microsatellite markers will be useful for studies of population genetic structure and genetic variability of the field gudgeon.     

Temperature and biomass influences on interannual changes in CO2 exchange in an alpine meadow on the Qinghai-Tibetan Plateau

Three years of eddy covariance measurements were used to characterize the seasonal and interannual variability of the CO₂ fluxes above an alpine meadow (3250 m a.s.l.) on the Qinghai‐Tibetan Plateau, China. This alpine meadow was a weak sink for atmospheric CO₂, with a net ecosystem production (NEP) of 78.5, 91.7, and 192.5 g C m^?2 yr^?1 in 2002, 2003, and 2004, respectively. The prominent, high NEP in 2004 resulted from the combination of high gross primary production (GPP) and low ecosystem respiration (R_e) during the growing season. The period of net absorption of CO₂ in 2004, 179 days, was 10 days longer than that in 2002 and 5 days longer than that in 2003. Moreover, the date on which the mean air temperature first exceeded 5.0°C was 10 days earlier in 2004 (DOY110) than in 2002 or 2003. This date agrees well with that on which the green aboveground biomass (Green AGB) started to increase. The relationship between light‐use efficiency and Green AGB was similar among the three years. In 2002, however, earlier senescence possibly caused low autumn GPP, and thus the annual NEP, to be lower. The low summertime R_e in 2004 was apparently caused by lower soil temperatures and the relatively lower temperature dependence of R_e in comparison with the other years. These results suggest that (1) the Qinghai‐Tibetan Plateau plays a potentially significant role in global carbon sequestration, because alpine meadow covers about one‐third of this vast plateau, and (2) the annual NEP in the alpine meadow was comprehensively controlled by the temperature environment, including its effect on biomass growth.     

INDUCTION OF CELLULAR PROCESSES CONTAINING COLLAGENASE AND RETINOID BY INTEGRIN-BINDING TO INTERSTITIAL COLLAGEN IN HEPATIC STELLATE CELL CULTURE

Cultered hepatic stellate cells were induced to elongate long, multipolar cellular processes by interstitial collagen gel used as a substratum, as compared to flattened or round cell shapes on polystyrene surface or on Matrigel containing the basement membrane components, respectively. The process induction was inhibited by several reagents as follows: (1) anti-integrin α2 antibody; (2) an oligopeptide, DGEA, an integrin-binding sequence in type I collagen molecule; (3) wortmannin, a phosphatidylinositol 3-kinase inhibitor. Protein tyrosine phosphorylation was enhanced throughout cells including cellular processes by culturing on type I collagen gel. Dual fluorescence staining showed that the core of the processes contained microtubules, whereas the periphery of the processes comprised fibrillar actin. Thus, the process extension was found to depend on integrin-binding to type I collagen fibres, followed by signal transduction and cytoskeleton assembly. The cellular processes included interstitial collagenase and vitamin A-containing lipid droplets. The lipid droplets and vitamin A-autofluorescence were increased by retinyl acetate addition to the culture medium, suggesting an important role of processes in hepatic stellate cell function.     

Isolation and characterization of polymorphic microsatellite DNA markers in the Japanese eight‐barbel loach,Lefua echigonia

We isolated and characterized 17 polymorphic microsatellite loci for the Japanese eight‐barbel loach, Lefua echigonia, an endangered freshwater species in streams including agricultural canals in Japan. The number of observed alleles for each locus ranged from two to nine, and the values of observed and expected heterozygosities ranged from 0.125 to 0.844 and from 0.148 to 0.876, respectively. All loci conformed to Hardy–Weinberg equilibrium. Genetic linkage disequilibrium analysis between all pairs of the loci showed no significant departure from the null hypothesis between any of the loci.     

THREE-DIMENSIONAL STRUCTURE OF EXTRACELLULAR MATRIX REVERSIBLY REGULATES MORPHOLOGY,PROLIFERATION AND COLLAGEN METABOLISM OF PERISINUSOIDAL STELLATE CELLS (VITAMIN A-STORING CELLS)

The three-dimensional structure of the extracellular substratum was found to regulate reversibly the morphology, proliferation and collagen synthesis of perisinusoidal stellate cells (lipocytes, i.e. fat-storing ‘Ito’ cells). On non-coated polystyrene and type I collagen-coated culture dishes, the cells spread well and extended their cellular processes. On the surface of type I collagen gels, the cells gathered and formed a mesh-like structure. However, in type I collagen gel where the cells were surrounded by type I collagen three-dimensionally, the cells extended their fine cellular processes and resembled the star-shaped stellate cells seenin vivo. The cell proliferation was more prominent in culture dishes coated with type I collagen or in polystyrene culture dishes than on or in type I collagen gels. The collagen synthesis was affected in the same manner. These data indicate that the nature and the three-dimensional structure of the extracellular matrix (ECM) can regulate morphology, proliferation and functions of the perisinusoidal stellate cells. In order to examine the reversibility of these regulations, we liberated cultured cells with trypsin or with purified bacterial collagenase and re-seeded them onto or into each substratum. The cells changed their shape, rate of proliferation and collagen synthesis according to each new substratum. These results indicate that the three-dimensional structure of ECM reversibly regulates the morphology, proliferation rate and functions of the perisinusoidal stellate cells.     

Erythrocyte Membrane-specific Antigens common to Several Species of Rodentia

THE rare existence of organ-specific antisera transcending species differences was pointed out by Coombs¹. Similar new organ, or “erythrocyte-specific”, antisera reacting selectively to the erythrocytes of several species of Myomorpha are described here. The antisera, “anti-A”, were prepared by the method of Adachi and Furusawa²: adult guinea-pigs were sensitized with the “antigen-A” (the protein portion of dd mouse erythrocyte membrane). The detailed procedure for preparing labelled antibody, the staining method and its specific reactivity to mouse erythrocytic cells have been reported before³. Circulating erythrocytes from various animals were stained with the fluorescein isothiocyanate-labelled “anti-A”. Smeared cell preparations were fixed with acetone at ? 20° C for 20 min and incubated with the labelled antisera, which had been thoroughly absorbed with the emulsion of mouse liver and kidney to remove the cross-reacting antibodies, at 37° C for 90 min. A light microscope with a darkfield condenser was used for the fluorescent observations using Orsen's interference filter system. Clear fluorescent reactions, though of varied intensities, were observed with those animals classified as Myomorpha, that is, mouse, rat, golden hamster and Chinese hamster (Table 1, Fig. 1). Mammalian erythrocytes other than those of the guinea-pig used as the sensitized animal showed faint fluorescences. Nucleated erythrocytes of the chick, quail, turtle, toad and goldfish were negative to the reaction. The erythrocyte-specific reactivity of the labelled antisera was examined with the liver, kidney and thymus cells of the animals whose erythrocytes displayed intense fluorescences; they showed, however, no fluorescence.     

Carbon dioxide balance of a tropical peat swamp forest in Kalimantan, Indonesia

Tropical peatlands, which coexist with swamp forests, have accumulated vast amounts of carbon as soil organic matter. Since the 1970s, however, deforestation and drainage have progressed on an enormous scale. In addition, El Niño and Southern Oscillation (ENSO) drought and large‐scale fires, which grow larger under the drought condition, are accelerating peatland devastation. That devastation enhances decomposition of soil organic matter and increases the carbon release to the atmosphere as CO₂. This phenomenon suggests that tropical peatlands have already become a large CO₂ source, but related quantitative information is limited. Therefore, we evaluated the CO₂ balance of a tropical peat swamp forest in Central Kalimantan, Indonesia, using 3 years of CO₂ fluxes measured using the eddy covariance technique from 2002 through 2004. The forest was disturbed by drainage; consequently, groundwater level (GL) was reduced. The net ecosystem CO₂ production (NEP) measurements showed seasonal variation, which was slightly positive or almost zero in the early dry season, and most‐negative late in the dry season or early the rainy season. This seasonality is attributable to the seasonal pattern of climate, tree phenology and fires. Slightly positive NEP resulted from smaller ecosystem respiration (RE) and larger gross primary production (GPP) under conditions of high photosynthetic photon flux density (PPFD) and large leaf area index (LAI). The most‐negative NEP resulted from smaller GPP and larger RE. The smaller GPP was related to high vapor pressure deficit (VPD), small LAI and low PPFD because of smoke from fires. The larger RE was related to low GL. Annual NEP values were estimated respectively as −602, −382 and −313 g C m⁻² yr⁻¹ for 2002, 2003 and 2004. These negative NEP values show that the tropical peat swamp forest, disturbed by drainage, functioned as a CO₂ source. That source intensity was highest in 2002, an ENSO year, mainly because of low PPFD caused by dense smoke emitted from large fires.