Subducted oceanic lithosphere is composed of two chemically distinct layers, namely basaltic (crustal) and peridotitic (mantle) layers. Recent mineral physics observations suggest that the crustal and mantle components of subducted oceanic lithosphere have distinct densities and viscosities. The deformation of such stratified oceanic lithosphere as it collides with the 660km discontinuity is examined using a simple analytical model. It is shown that the separation of the crustal component can occur through a small scale folding (10-20km) if the viscosity of the crustal (garnetite) layer is significantly higher than that of the surrounding mantle (-1021Pa s) but is less than -1023Pa s, leading to a garnet-enriched transition zone behind subduction zones.
A ground water sample from cracks of granitic wall was taken as a case study. It is shown that the characteristics of the lanthanide tetrad phenomenon can be demonstrated by the cusp-spanning pattern and the aberration diagram which indicates the aberrations of observed points from lines defined by the cusp points. It is revealed that, unlike the lanthanide partitioning between the aqueous and organic phases, the lanthanide distribution curve for the studied case representing the water-rock interaction is not monotonously linear, except the tetrad aberration, but appears to consist of four stretches with relatively sharp breaks of cusp-spanning pattern at cusp points between the first and the second segments and between the third and the fourth ones. The effects of the position assumed for cusps on the quadratic coefficients and on the aberration diagram have been mathematically evaluated. Employing the method proposed by Masuda and his coresearchers, the aberration diagrams for the 4th, 3rd and 2nd tetrads are not affected so much by the shift (±0.1 abscissa unit) of the position assumed for crossing, but the effect on the 1st tetrad is not quite negligible.
The Hyogo-ken Nanbu Earthquake of January 17, 1995 caused severe damage to buildings, highway bridges, railways, lifeline systems, port facilities, and so on. This event is the first instance in which engineering structures which were designed for the highest seismic forces in the world have been subjected to such destructive ground motions. This paper shows several calculated response spectra for the Kobe record together with the Sylmar record obtained during the Northridge Earthquake, which occurred on exactly the same day of 1994. Comparing these response spectra with those for previously obtained historical earthquake records, extremely high damage potential is revealed for near field earthquake ground motion. Urgent retrofit of old structures and re-examination of present seismic design codes are essential.
Sigma factors introduce sequence-specificity to DNA recognition by eubacterial RNA polymerases. Two domains of the factors, domains 4 and 2, bind, respectively, to the -35 and -10 sites in the promoters. We compare the amino acid sequences of the two domains of the major sigma subfamily (the σ70 subfamily) with those of other DNA-binding proteins (i.e. BirA, histone H5, LexA, and DtxR) of which the 3D structures are known. It is concluded that each of the two sigma domains probably has three α-helices, and that the third α-helix binds to the DNA. Possible ways in which the two domains are combined along the same DNA and contact patterns between amino acid residues in the two domains and the DNA bases are discussed.
Acetylcholine (ACh) is present in human blood and localized in T-lymphocytes which exhibit ACh-synthesizing activity. As the final step towards clarifying the origin of ACh present in the blood, we elucidated the enzyme involved in ACh synthesis in T-lymphocytes by detecting the mRNA for choline acetyltransferase (ChAT), which is known to catalyze ACh synthesis in the nervous system. The ChAT mRNA in the MOLT-3 human leukemic T-cell line was amplified by reverse transcription-polymerase chain reaction (RT-PCR) using specific order and reverse primers. A single specific RT-PCR product was observed on agarose gel. The sequence of the RT-PCR product of MOLT-3 was completely identical with nucleotide positions 322-973 of human brain ChAT cDNA. Western blot analysis with an antibody to ChAT confirmed the presence of ChAT protein in MOLT-3. These findings demonstrate that mRNA for the same ChAT as that in the nervous system is expressed in T-lymphocytes, and indicate that ACh synthesized by ChAT in T-lymphocytes is the origin of ACh in the blood.
Carotenoids have been known to be effective in preventing a variety of diseases such as cancers and cardiovascular disorders. Mammalian cells cannot synthesize carotenoids and rely on a dietary source for their intake. Here we report the establishment of mammalian cells synthesizing phytoene, a kind of carotenoid, by introduction of thecrtB gene, phytoene synthase gene, which was previously cloned from a bacterium, Erwiuia uredovora. The phytoene-producing cells acquired a resistance against oxidative stress induced by Fe3+/adenosine 5'-diphosphate. The data suggest the feasibility of a genetic chemoprevention for oxidative stress-related disorders by endogenous synthesis of phytoene in mammalian cells.
We studied the allelic distributions of 48-base pair repeat polymorphism of the dopamine D4 receptor (DRD4) gene in two groups of schizophrenic patients, one with any schizophrenic member in the family (L(+) group) and the other without schizophrenic family histories (L(-) group), and healthy controls. The frequency of the sum of the alleles of 4, 5, and 6 repeats in the L(+) group was significantly higher than the controls. The frequency of the allele of 4 repeats in the L(-) group was significantly higher than the controls. These results show positive allelic associations between DRD4 polymorphism and each of the two groups of schizophrenic patients.
Applicability of the DEV analysis is investigated to various proteins other than trypsin. The strategies A and B are mainly employed to identify possible functional sites of protein. The strategies C and D help to improve assignment of a functional system, and a higher-dimensional model constructed by the DEV analysis gives an essential knowledge of functional sites of protein. Some functional sites were found to locate near active sites that are already known experimentally, and the other have proved of another function. The DEV analysis, based on a simple logic, has rather mathematical nature as well as topological concept.