Scolicia shirahamensis isp. nov.: a triple-corded scolicia and its ichnological implications

Abstract

Peculiar meniscate burrows with three sediment cords occur in early to middle Miocene tidal-flat deposits of southwestern Japan. Two of the cords are situated at the bottom and the other is at its center. Detailed observations of the burrow structures and comparative neoichnological studies of modern spatangoid burrows in a tidal flat revealed that the former two were true drainage tubes and the latter was fecal in origin. The trace fossil was thus assigned to the ichnogenus Scolicia. Based on these findings, a new ichnospecies Scolicia shirahamensis isp. nov. has been described here. The central sediment cord is seemingly identical to the drainage tube of the ichnogenus Bichordites, another ichnogenus that has been commonly ascribed to a fossil spatangoid burrow, similar to Scolicia. Careless ichnogeneric identification of a spatangoid burrow, based only on the central sediment cord, therefore, may produce an incorrect identification.     

Molecular engineering of Rhizopus oryzae lipase using a combinatorial protein library constructed on the yeast cell surface

We constructed a combinatorial yeast library through cell-surface display of the pro- and mature region of lipase from Rhizopus oryzae (ProROL) and obtained clones retaining lipase activity in fluorescent plate assay. The initial reaction rates of hydrolysis and methanolysis could be measured directly as whole-cell biocatalyst without complex treatments such as concentration, purification, and immobilization. The selected clones showed wide-ranging variation of reaction specificity. The K138R mutant showed a 1.3-fold shift of reaction specificity toward methanolysis compared to the wild type, while the V-95D, I53V, P-96S/F196Y, and Q128H/Q197L mutants showed shifts toward hydrolysis of 1.6–5.9-fold. Predictions of the mutants’ three-dimensional structure suggested that the hydrogen-bond distance between threonine 83 and aspartic acid 92 may influence reaction specificity, which shifted toward hydrolysis in mutants where this distance was shorter than in the wild type, but toward methanolysis where it was longer. The positions of amino acid residues (aa) 53, 138 and 196 in ProROL are considered the sites that influence hydrogen-bond distance and change reaction specificity. Construction of a surface-displayed combinatorial library in yeast cells is thus a powerful tool in accelerating the combinatorial approach to enzyme engineering and novel whole-cell biocatalyst development.     

Fructose 1,6-diphosphate augments paraquat injury in isolated dog lungs.

Paraquat (PQ; 1,1'-dimethyl-4,4'-bipyridylium dichloride), a widely used herbicide, causes pulmonary edema by a cyclic oxidation and reduction reaction with oxygen molecules with the production of oxygen free radicals. Because fructose 1,6-diphosphate (FDP) has recently been shown to inhibit the generation of oxygen free radicals by activated neutrophils, we determined the effects of FDP on PQ-induced increase in microvascular permeability in isolated blood-perfused dog lungs. Vascular permeability was assessed using the capillary filtration coefficient (Kf,c) and isogravimetric capillary pressure (Pc,i). There was no change in these variables over 5 h in the control lungs treated with saline (n = 5). A significant increase in Kf,c and a decrease in Pc,i, both of which indicated increased vascular permeability, were observed at 5 h of perfusion with 4 x 10(-3) M PQ (n = 5). Unexpectedly, an increase in microvascular permeability occurred within 4 h after administration of PQ in the lungs that were pretreated with FDP (2.7-14.2 mM, n = 6). Moreover the increases of Kf,c in the FDP-pretreated lungs were significantly greater than those in the lungs treated with PQ alone. Also, the final-to-initial lung weight ratio of the FDP-pretreated group was greater than those of the other groups. Thus the FDP dose used in the present study accentuated rather than prevented the PQ lung injury.     

Isolation and identification of phenols in oil of vetiver

Several rare phenols, including 4-vinylphenol, 4-vinyl-2-methoxyphenol and trans-isoeugenol, were identified in oil of vetiver.     

The radiation response of SCCVII tumor cells in C3H/He mice varies with the irradiation conditions

The radiation response of SCCVII tumor cells in C3H/He mice under various irradiation conditions was studied using an in vivo-in vitro assay. When tumor-bearing mice were irradiated without anesthesia or physical restraint, the tumor had a hypoxic fraction of 5.4%. Both anesthesia and immobilization of the tumor-bearing leg with adhesive tape produced significant increases in the hypoxic fraction (23 and 28%, respectively). Restraining the mouse in a jig without immobilizing the tumor-bearing leg also increased the hypoxic fraction (13%).     

Involvement of prostaglandin-producing pathway in the cytotoxic action of tumor necrosis factor.

To elucidate the cytotoxic mechanism of tumor necrosis factor (TNF), we isolated TNF-resistant sublines of L929 cells. As compared with L929 cells, TNF-resistant cells retained similar number and affinity of TNF-binding sites, and showed a similar growth rate. TNF stimulated arachidonate release from L929 cells, while no stimulation was observed at all in TNF-resistant cells tested. The cytotoxic action of TNF on L929 cells was inhibited by indomethacin, suggesting that prostaglandin may be involved in the action. Therefore, TNF-stimulated prostaglandin production was examined in L929 and TNF-resistant sublines. The amount of PGE2 produced by L929 cells was increased more than 5-fold after the addition of TNF, whereas the amount of PGE2 did not change in the resistant sublines following addition of the factor. TNF-stimulated arachidonate release and PGE2 production were reversed by islet-activating protein (IAP)-treatment of L929 cells. These results suggest that arachidonate release and subsequent prostaglandin production are important for the cytotoxic action of TNF and that these processes are mediated by GTP-binding protein (G protein) that is coupled to the TNF-receptor.