Unique Pattern of Gene Expression in the Erythroid Precursor Cells

Erythroid cells were fractionated by preformed Percoll density gradient from livers of 12.5 day old mouse fetuses. With combination of lysing of mature erythroid cells, the CFU-E (colony forming unit of erythroid) was enriched as high as 30% pure. The mRNA levels of the rt-genes previously cloned as genes expressed in the reticulocytes are estimated in the fractionated erythroid cells. These rt-genes show a drastic change in expression during erythroid differentiation; Their expression was not detectable at the CFU-E cell stage. But it reached to maximum at the polychromatic erythroblast (stage I) and then decreases with maturation. The result suggests that mRNA synthesis of these rt-genes may be induced after the stimulation of erythropoietin.     

Cloning and Characterization of Genes Expressed in the Mouse Reticulocytes

In mouse reticulocytes, approximately 250 middle abundant-rare class messages were estimated to be present besides globin mRNA (OBINATA and IKAWA, 1980). Approximately 200 independent genomic clones (rt-clones) expressed in the mouse reticulocyte mRNAs were obtained from a mouse gene library. Surprisingly, most of the rt-clones are shown to be expressed even in non-erythroid tissues significantly. By the plaque hybridization method with 133 rt-clones, the pattern of expression of these genes was examined at different stages of erythroid cell maturation.     

Aphids decelerate litter nitrogen mineralisation through changes in litter quality

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VINYL PHEOPORPHYRIN A5 IN THE INNER SEED COATS OF PUMPKINS

The pigments contained in the inner seed coats of Cucurbitapepo, C. maxima and C. moschata were investigated spectroscopicallyusing both intact tissues and their ether extracts. The pigment(s) contained in C. pepo and C. maxima was inferred to be "protochlorophyll"and/or Mg vinyl pheoporphyrin a₅ which are indistinguishablefrom each other by mere spectroscopic observations. The coatsof C. moschata were found to contain Mg-free vinyl pheoporphyrina₅ which has so far been reported to exist only in some Chlorellamutants. The spectra of these pigments in intact tissues wereremarkably different from those of the ether extracts, indicatingthe profound difference in their physical states in vitro andin vivo. It was discussed that the "protochlorophyll b" reportedearlier by SEYBOLD and EGLE might have been vinyl pheoporphyrina₁. (Received July 14, 1960; )     

Role of extrafloral nectaries of Vicia faba in attraction of ants and herbivore exclusion by ants

We directly evaluated the role of extrafloral nectaries (EFN) in ant attraction and herbivore exclusion by experimental removal of EFN in the laboratory. When EFN of Vicia faba Linnaeus (Leguminosae) were artificially removed, the number of workers of Tetramorium tsushimae Emery (Hymenoptera: Formicidae) visiting the plant decreased, and the efficiency of herbivore exclusion by ants also decreased. Herbivore exclusion by ants was mostly ineffective on a plant when less than four workers visited the plant, but when more than four workers visited, the time a herbivore resided on the plant decreased rapidly with increasing numbers of visiting ants. Therefore, the efficiency of herbivore exclusion from a plant is determined by the number of ants visiting, and EFN play an important role in ant attraction.     

CHANGE OF FATTY ACID COMPOSITION OF CHLORELLA ELLIPSOIDEA DURING ITS CELL CYCLE

The lipids extracted from Chlorella cells at different developmentalstages were separated by chromatography on silicic acid into"nonpolar" (chloroform-eluate) and "polar" (methanol-eluate)lipid fractions. The lipids were also subjected to florisilchromatography to fractionate neutral glycerides and free fattyacids. Gas-liquid chromatographic analysis of these fractions has revealeda marked difference in their fatty acid compositions which werefound to undergo characteristic changes during the course ofalgal cell cycle. It was found that the fatty acids in the "nonpolar"lipid (fat) fraction are synthesized during the growth phasein the light and consumed during the process of cellular division. (Received September 24, 1966; )     

How does flowering magnitude affect seed survival in Shorea pilosa (Dipterocarpaceae) at the predispersal stage in Malaysia?

General flowering (GF), a supra-annual, irregular fluctuation in flowering and seeding at the community level, is a phenomenon unique to the tropical rainforests of South-East Asia. To test the animal pollination and predator satiation hypotheses, which are the main hypotheses that attempt to explain the ultimate cause of GF, we conducted a bagging experiment after the flowering of Shorea pilosa (Dipterocarpaceae). Seed survival at the predispersal stage was divided into two stages (1–30 days and > 30 days after flowering) and we compared the results between treatments and between GF and non-GF periods using a survival analysis. Survival during the GF period at both stages was significantly higher than during non-GF periods, suggesting that both hypotheses were supported and that synchronous flowering with GF benefits the reproductive success of S. pilosa .     

Selective light transmittance of translucent bracts in the Himalayan giant glasshouse plant Rheum nobile Hook. f. & Thomson (Polygonaceae)

Translucent bract transmittance of ultraviolet (UV) to infrared (IR) radiation (between 320 and 800 nm) and leaf anatomy were examined in a glasshouse plant, Rheum nobile Hook. f. & Thomson (Polygonaceae) to assess the function of avoiding injury by UV radiation while keeping the inflorescence warm by photosynthetically active (PA) and IR radiation. Although the translucent bracts and rosulate leaves transmitted little UV radiation, the former always transmit more PA and IR radiation. Additionally, the bracts transmit much more scattered solar radiation than direct radiation. The bracts are also anatomically different from the rosulate leaves. They have two or three layers of mesophyll cells with neither palisade nor spongy parenchymatous cells; in addition, the uppermost layer of mesophyll and the epidermis stain easily, and both are thought to play a role in attenuating UV radiation. The leaf epidermis of many land plants has UV absorbing pigments such as flavonoids, which absorb almost all UV radiation. Thus the role of the bracts of R. nobile is to protect the reproductive organs by absorbing UV radiation and to keep them warm by transmitting PA and IR radiation. The bracts are believed to have adapted function and form to the environment, in particular, to the weather conditions of the eastern Himalaya.     

Pollen development of Rheum nobile Hook.f. & Thomson (Polygonaceae), with reference to its sterility induced by bract removal

The Himalayan alpine herb, Rheum nobile , terminates in a stout conical compound raceme concealed by large translucent bracts. It bears many fruits even under hostile conditions such as low temperature or persistent cloudy weather. To clarify the role of the bracts, the structure and the development of the pollen grains were examined after removing the bracts to expose the flowers to the open air for 9 days. Half of the individuals with bracts removed showed 0 to 1 % of pollen stainability and the pollen grains were variable in shape and size. It was also observed that the bracts of Rheum nobile increased the temperature of inflorescence by about 10deg;C above ambient daytime temperatures. These results suggest that one of the causes for the inhibition of pollen development was low temperature. The remainder, however, indicated high stainability of 70–100%. It is suggested that the extreme difference of pollen stainability between two groups of Rheum nobile exposed to the surroundings may be related to the stage of microsporogenesis. Bracts of Rheum nobile might play an important role in normal reproduction under low temperature at high altitudes.