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; )     

Development of compound microsatellite markers in the harmful dinoflagellate Cochlodinium polykrikoides (Dinophyceae)

We isolated 15 polymorphic microsatellites from Cochlodinium polykrikoides. These loci provide a class of highly variable genetic markers, as the number of alleles ranged from two to 15, and the estimate of gene diversity was from 0.083 to 0.880 across the 15 microsatellites. We consider that these loci have a potential to reveal the genetic structure and gene flow among C. polykrikoides populations.     

水分胁迫下臭柏（Sabina vulgaris Ant.）光合特性和色素组成的季节变化

在室内砾耕栽培条件下,通过培养液中加入PEG(Polyethylene glycol 分子量为6000)以调节溶液渗透势,设置对照、弱水分胁迫和强水分胁迫3种处理 (培养液渗透势分别为0.02,-0.1,-0.34 MPa), 从1997年开始对臭柏进行长期干旱胁迫模拟实验.2003年测定了臭柏叶片光合色素和光合特性的季节变化.结果表明:对照区气孔导度季节变化在5月和9月份形成了典型的双峰曲线.尽管对照区的气孔导度明显高于其他两个处理,但日光合量却低于弱水分胁迫区.3个处理Chl a/b的比值在11月至翌年3月的低温期内均升高,以强水分胁迫区的增幅最大,其它月份该比值在3个处理之间没有显著的差异.3个处理的叶绿素总量(Chl a+b)在生长季的5～9月份均有不同程度的上升,但其中以强水分胁迫区增幅最小.在11月至翌年3月的低温期,各处理均大幅提高叶黄素总量(V+A+Z)和热耗散色素比例(A+Z)/(V+A+Z) (V:紫黄质、A:单环氧玉米黄质、Z:玉米黄质);在5～7月份的生长高峰期,各处理则明显降低了叶黄素总量和热耗散色素比例.这种趋势在强水分胁迫区表现的更为显著.     

Genetic structuring and transfer of marine dinoflagellate Cochlodinium polykrikoides in Japanese and Korean coastal waters revealed by microsatellites

To determine the process of population expansion and ascertain the origin of the Sea of Japan population, in a noxious red tide forming dinoflagellate Cochlodinium polykrikoides , 13 samples, isolated from 11 different localities in Japanese and Korean coasts, were analysed using 10 polymorphic microsatellites. Analyses by nonmetric multidimensional scaling plots of pairwise F _ST, global amova , and genetic admixture analysis identified three clusters — the Sea of Japan populations, Yatsushiro Sea (Kumamoto Pref.) populations, and other populations — indicating genetic structuring of the 13 samples into three distinct populations. In the proportion of shared alleles by pairwise individuals ( P _SAxy) analyses between the Sea of Japan and the other samples, P _SAxy was extremely low compared with that among the Sea of Japan or among other samples, indicating that a large genetic barrier has occurred between the populations. No significant relationship of isolation-by-distance patterns and almost no genetic distance were detected between pairwise samples of the Sea of Japan, although there is a maximal distance of > 600 km between samples. In addition, P _SAxy data among the samples were extremely high compared with those among other samples, clearly showing that a large-scale transfer from west to east has occurred via the Tushima Warm Current. In the P _SAxy data of the Seto Inland Sea and Pacific samples, individuals showing relatively high P _SAxy were concentrated in the three areas of Nagasaki, Harima, and Mie, suggesting that frequent transfer may have occurred by human-assisted dispersal, although Nagasaki and Mie are separated by a distance of approximately 700 km.     

Inhibition of development of anti-predator morphology in the small cladoceran Bosmina by an insecticide: impact of an anthropogenic chemical on prey–predator interactions

1. The combined effect of the insecticide carbaryl and the predator (Leptodora kindtii) kairomone was assessed on the development of protuberant morphology in the small cladoceran Bosmina fatalis, a feature which evolved originally as a response to the kairomone. The experiment showed that Bosmina changed its morphology in response to the kairomone, but development was inhibited by carbaryl at a sub‐lethal concentration even in the presence of the kairomone. At the same time, reduction of fecundity was observed in animals exposed to carbaryl. 2. A short‐term feeding experiment (B. fatalis versus Leptodora) indicated that such low concentrations of the insecticide had no impact on predation by Leptodora. Thus, it is suggested that the inhibition of development of anti‐predatory defences in Bosmina can increase its vulnerability to predation. 3. Such disturbance of chemical communication by the insecticide reduces the individual survival rate of prey Bosmina in the environment with high predator density. On the other hand, reduction of fecundity may result in decreased population growth rate of animals. 4. The impact of the insecticide on the anti‐predator morphology in Bosmina (inhibition) was opposite to that in Daphnia (enhancement). This suggests that biochemical induction processes in the development of anti‐predatory morphology are evolutionally different between Daphnia and Bosmina.     

Genetic modification of the fatty acid unsaturation of phosphatidylglycerol in chloroplasts alters the sensitivity of tobacco plants to cold stress

The cis‐unsaturated molecular species of phosphatidylglycerol (PG) in chloroplasts have been implicated in the chilling sensitivity of plants. Homozygous lines of transgenic tobacco (Nicotiana tabacum) that overexpressed the cDNA for glycerol‐3‐phosphate acyltransferase, a key enzyme in the determination of the extent of cis‐unsaturation of PG, were established from a chilling‐sensitive squash (Cucurbita moschata). In transgenic plants, the proportion of saturated plus trans‐monounsaturated molecular species of PG increased from 24 to 65%. However, this change did not affect the architecture of the chloroplasts. Chilling stress decreased the growth and biomass production of young seedlings of transgenic plants more severely than those of wild‐type plants, and this observation suggests that the changes in the proportion of cis‐unsaturated PG affected not only leaves but also developing plants. Chilling stress also damaged inflorescences. In particular, the abscission of flower buds and inflorescence meristems from transgenic plants occurred more frequently than that from wild‐type plants. Thus, it is likely that decreases in the proportion of cis‐unsaturated PG enhanced the sensitivity to chilling of reproductive organs.     

Ion gradients in xylem exudate and guttation fluid related to tissue ion levels along primary leaves of barley

The concentration of ions in plant cells and tissues is an essential factor in determining physiological function. In the present study, we established that concentration gradients of mobile ions exist in both xylem exudates and tissues within a barley (Hordeum vulgare) primary leaf. For K⁺ and NO₃^?, ion concentrations generally decreased from the leaf base to the tip in both xylem exudates and tissues. Ion gradients were also found for Pi and Cl^? in the xylem. The hydathode strongly absorbed Pi and re‐translocated it to the rest of the plant, whereas Cl^? was extruded. The ion concentration gradients developed early during leaf growth, increased as the tissue aged and remained under both high and low transpiration conditions. Measurement of the expression profiles of Pi, K⁺ and NO₃^? transporters along the longitudinal axis of the leaf revealed that some transporters are more expressed at the hydathode, but for most transporters, there was no significant variation along the leaf. The mechanisms by which longitudinal ion gradients develop in leaves and their physiological functions are discussed.     

Isolation and characterization of new microsatellite markers from the Japanese flounder (Paralichthys olivaceus)

The isolation and characterization of eight polymorphic microsatellite loci from a Japanese flounder partial genomic library are reported. The eight markers isolated in this study were highly polymorphic and their positions on the linkage genome map of the Japanese flounder were determined. Therefore, they are useful for ecological studies of wild populations. These markers are more effective than other markers with no information of chromosomal locations.