穆珠朗玛峰地区土壤中稀土元素的含量和分布

本文论述了珠穆朗玛峯地区土壤中稀土元素的含量,以及它们在土壤中的分布模式,并发现土壤中稀土元素的含量水平在很大程度上受土壤母质的制约。     

Induction of tributyltin-binding protein type 2 in Japanese flounder, Paralichthys olivaceus, by exposure to tributyltin-d27

In this study, individual Japanese flounder were intraperitoneally injected with 2 μg tributyltin-d27 (TBT-d27) fish⁻¹. Blood samples were collected on day 7 after injection. TBT-binding protein types 1 and 2 (TBT-bp1, -bp2) in the blood serum were quantified by western blotting analysis. As a result, the concentration of TBT-bp2 in TBT-d27 treated group increased to 220% of that in the solvent control, whereas the TBT-bp1 concentration decreased to 65% of that in the solvent control. Additionally, a positive relationship between the concentrations of TBT-bp2 and TBT was observed in blood sera of wild and cultured flounder. We suggest that TBT-bp2 is produced in response to TBT exposure and may play an important role in fish physiology.     

DNA strand breaks (comet assay) and embryo development effects in grass shrimp (Palaemonetes pugio) embryos after exposure to genotoxicants.

Grass shrimp embryos develop in egg sacs (stages 1-10) attached to the female for 14-20 days after which they 'hatch' from the egg sacs into a swimming zoea stage (stage 11). Until they emerge from the egg sacs, embryos depend on lipids and lipovitellin stored within the egg. The percent of embryos which hatch after exposure to toxicants relative to controls was the basis of an embryo development assay. Exposure of embryos to chromium(III) chloride, sodium chromate, mercuric chloride, and 2-methyl-1,2-naphthoquinone (MNQ) resulted in a reduced hatching rate. In addition to effects on embryo development, DNA strand damage tests were carried out on contaminant-exposed embryos, using the single-cell electrophoresis method often referred to as comet assay. Development of stage 4 embryos was more affected by MNQ exposure than stage 7 embryos. The hatching rates of stages 4 and 7 embryos exposed to MNQ (172 micrograms/l) were 0 and 90%, respectively. DNA strand damage, measured as DNA tail moments, were 3.4 and 4.4, respectively. Thus, exposure of an early embryo stage to MNQ prevented full embryo development while development of later embryo stages was not affected. It may be that the DNA repair systems are more efficient in later embryo stages than in early stages and thus DNA damaged in the early stages affects development.     

Is bacteriophage φX174 DNA a message from an extraterrestrial intelligence?

We speculate that a simple biological system carrying a message and capable of self-replication in suitable environments may be one possible channel for interstellar communication. A preliminary experiment was performed to test the hypothesis that phage φC174 DNA carries a message from an advanced civilization.     

Aeromagnetic surveys in the seas around Japan in 1980

Aeromagnetic surveys in the seas around Japan were carried out in 1979 to 1980 by a YS-11 aircraft of the Maritime Safety Agency of Japan using a new type of airborne magnetometer system. The new type of airborne magnetometer system consists of a ring-core type three-component fluxgate magnetometer, an inertial sensing system, a fish-eye camera to measure the true north, an 8-bit microcomputer and a proton magnetometer. The VLF/OMEGA system is used to fix the position of the aircraft. Tracks extended to about 600 nautical miles off the coast of the Japanese islands in the Sea of Japan and the North-West Pacific Ocean. Average spacing between tracks was about 80 miles. The flights were carried out at an altitude of 9500 feet. From the survey results, magnetic charts of the seven geomagnetic elements for 1980 over the sea around Japan were compiled by the method of least squares using a polynomial. Also, the contour charts of secular variation in 1980 were compiled.     

Cell contact-dependent lethal effect of the dinoflagellate Heterocapsa circularisquama on phytoplankton–phytoplankton interactions

We used bi-algal culture experiments to investigate and verify the roles of growth interaction between Heterocapsa circularisquama and Prorocentrum dentatum in monospecific bloom formation. Growth of H. circularisquama was slightly inhibited when inoculated at 10² cells mL^–1 along with P. dentatum at 10⁴ cells mL^–1. In other combinations of inoculation densities, P. dentatum density rapidly decreased to extremely low levels in the presence of H. circularisquama. We used a mathematical model to simulate growth and interactions of H. circularisquama and P. dentatum in bi-algal cultures. The model indicates that one species will always inhibit the growth of the other and that the relative initial cell densities of the species are critical in determining the outcome. When cultured together under conditions without cell contact, growth of H. circularisquama and P. dentatum was not inhibited. As with P. dentatum, the growth of Heterosigma akashiwo and Skeletonema costatum was inhibited in intact cell suspensions with H. circularisquama, but a nontoxic species, Heterocapsa triquetra, did not affect the growth of P. dentatum or the other species. Similarly, cell suspensions of H. circularisquama showed hemolytic activity toward rabbit erythrocytes, but those of H. triquetra did not. In addition, the cell-free supernatant of H. circularisquama cultures showed no significant hemolytic activity. These results suggest that H. circularisquama causes lethality in P. dentatum by direct cell contact in which live-cell-mediated hemolytic activity might be a contributing factor.     

Displacement behavior of CH4 adsorbed on coals by injecting pure CO2, N2, and CO2–N2 mixture

Gas adsorption isotherms of Akabira coals were established for pure carbon dioxide (CO₂), methane (CH₄), and nitrogen (N₂). Experimental data fit well into the Langmuir model. The ratio of sorption capacity of CO₂, CH₄, and N₂ is 8.5:3.5:1 at a lower pressure (1.2 MPa) regime and becomes 5.5:2:1 when gas pressure increases to 6.0 MPa. The difference in sorption capacity of these three gases is explained by differences in the density of the three gases with increasing pressure. A coal–methane system partially saturated with CH₄ at 2.4 MPa adsorption pressure was experimentally studied. Desorption behavior of CH₄ by injecting pure CO₂ (at 3.0, 4.0, 5.0, and 6.0 MPa), and by injecting the CO₂–N₂ mixture and pure N₂ (at 3.0 and 6.0 MPa) were evaluated. Results indicate that the preferential sorption property of coal for CO₂ is significantly higher than that for CH₄ or N₂. CO₂ injection can displace almost all of the CH₄ adsorbed on coal. When modeling the CH₄–CO₂ binary and CH₂–CO₂–N₂ ternary adsorption system by using the extended Langmuir (EL) equation, the EL model always over-predicted the sorbed CO₂ value with a lower error, while under-predicting the sorbed CH₄ with a higher error. A part of CO₂ may dissolve into the solid organic structure of coal, besides its competitive adsorption with other gases. According to this explanation, the EL coefficients of CO₂ in EL equation were revised. The revised EL model proved to be very accurate in predicting sorbed ratio of multi-component gases on coals.     

Probable effects of CO2-induced climatic warming on the thermal environment of ponded shallow water

A physical model was developed for describing the thermal environment of ponded shallow water as a model for rice fields in relation to climatic conditions. The model was used to assess probable effects of CO₂-induced warming on the thermal conditions of ponded shallow water. It was assumed that an altered equilibrium climate was produced by atmospheric CO₂ which was twice that of present levels. The 1951–80 climatic means of Japan were used as baseline data. Water temperature and energy balance characteristics predicted from the model were compared between both climates. The most notable results were that water temperature under CO₂ doubling rose 2 to 4 °C. These increases in temperature would induce a remarkable northward shift of the 15 °C isotherm which characterizes the isochrone of safe transplanting dates for rice seedlings. CO₂-warming would have a considerable influence on the energy balance characteristics, intensifying the evaporation rate from the water surface. Changes in thermal conditions of rice fields due to CO₂-induced climatic warming are, therefore, expected to bring about significant effects on aquatic environments and the life forms they support.     

Essential cellular modules for the proliferation of the primitive cell

Bacteria appeared early in the evolution of cellular life on planet Earth, and therefore the universally essential genes or biological pathways found across bacterial domains may represent fundamental genetic or cellular systems used in early life. The essential genes and the minimal gene set required to support bacterial life have recently been experimentally and computationally identified. It is, however,still hard to estimate the ancient genes present in primitive cells compared to the essential genes in contemporary bacteria, because we do not know how ancestral primitive cells lived and proliferated, and therefore cannot directly evaluate the essentiality of the genes in ancestral primitive cells. The cell wall is normally essential for bacterial proliferation and cellular division of walled bacterial cells is normally highly controlled by the essential FtsZ cell division machinery. But, bacteria are capable of reverting to their cell wall deficient ancestral form, called the "L-form". Unlike "normal" cells, L-forms divide by a simple physical mechanism based on the effects of membrane dynamics, suggesting a mode of primitive proliferation before the appearance of the cell wall. In this review, we summarize the experimental and computational investigations of minimal gene sets and discuss the minimal cellular modules required to support the proliferation of primitive cells, based on L-form proliferation.