Identification of two metabolites induced by a butyrolactone autoregulator IM-2 in Streptomyces sp. FRI-5

Abstract In order to determine whether non-elastase-producing strains of Pseudomonas aeruginosa such as N-10, PA103 and IFO3080 can express foreign elastase genes, we introduced elastase genes from P. aeruginosa IFO3455 (elastase-producing) as well as from PA103 and N-10 into non-elastase-producing P. aeruginosa strains. Results suggested that gene expression, secretion, and precursor processing systems of elastase were essentially normal in P. aeruginosa N-10 and IFO3080. Our studies using various elastase genes showed that both the elastase structural gene and 5'-upstream regions of P. aeruginosa PA103 were also normal. This was confirmed by the finding that P. aeruginosa N-10 and IFO3080 which carry the PA103 elastase gene produced elastase. Several deleted or chimeric genes were constructed using the 5'-upstream regions of elastase genes from P. aeruginosa N-10 or PA103 and studies of expression revealed that two individual DNA bases seem to be important in suppressing P. aeruginosa N-10 elastase gene expression. Possible reasons for the lack of elastase in these non-elastase-producing strains are discussed.     

Recognition of rat liver and kidney nuclear T3 receptors by an antibody against c-erb A peptide

It has been reported that c-erb A encodes nuclear T3 receptors (NT3R). Based on the sequence of c-erb A cDNA, we synthesized a polypeptide consisting of 15 amino acids, the sequence of which has high homology between c-erb A alpha 1 and beta. The antibody against this c-erb A peptide not only immunoprecipitated rat liver and kidney NT3R but also inhibited T3 binding to NT3R. In a displacement study, the inhibition of [125I]T3-binding by the antibody was parallel to that by T3 in terms of the concentration of the competitor added in the incubation mixture. Scatchard analysis revealed that the antibody decreased the value for the association constant in a dose dependent manner. The antibody did not bind T3 itself. The results show that the antibody against c-erb A peptide recognizes rat liver and kidney NT3R and that the sequence encoding this peptide, the closest carboxyl-terminal of c-erb A may be critical or at least closely related to the hormone binding.     

Pyrophosphate-dependent phosphofructokinase from pollen: properties and possible roles in sugar metabolism

To evaluate the role of pyrophosphate-dependent phosphofructokinase (PFP. EC 2.7.1.90) in the sugar metabolism of pollen. its occurrence and properties were studied in pollen grains of several plants including camellia ( Camellia japonica L.). In all pollen samples, PFP was strongly activated by fructose-2,6-bisphosphate (F2,6BP), and the activity of F2,6BP-activated PFP was higher than that of phosphofructokinase (PFK. EC 2.7.1.11). PFP partially purified from camellia pollen required Mg²⁺ for activity with an optimum at 1 m M . and was almost unaflected by a variety of metabolites at 1 m M . Its molecular mass was around 220 kDa, and apparent K_m values for F6P, PP_i. F1, 6BP and P_i were 294, 4, 20 and 580 u M , respectively. The levels of F2.6BP. PP_i and F6P in camellia pollen were sufficent to support the forward reaction by PFP, and PFP, was 20- to 40-fold more active than PFK during pollen growth. These results suggest that pollen PFP plays a role in glycolysis but not gluconeogenesis. and the possible relevance of this to pollen tube growth is discussed.     

RADIATION EFFECTS ON CELL POPULATIONS IN THE INTESTINAL EPITHELIUM OF MICE AND ITS THEORY

Mice were exposed to 1000 R of X-rays to their trunks and sacrificed every day up to the tenth day after exposure. Cell counts were made on histological sections of the duodenum. The cell counts in the crypts were reduced to about 50% of the control value on the first day after exposure. The cell counts began to recover on the third day and an overshoot of 170% was observed on the fourth day; thereafter the crypt cell counts tended to return to the control level. The cell counts on the villi reached their minimum value on the third day after exposure. Following an overshoot on the sixth day, the villus cell counts returned to the control level by the tenth day. The above experimental results were analysed using a two-compartment model with a feedback term. A logistic proliferation was assumed for the proliferative crypt cells, while for the postmitotic villus cells the compartment was assumed to be a first in-first out type. The calculated results with this model are in general consistent with the experimental ones. The model seems to possess some essential features of the dynamics of cell renewal in the intestinal mucosa.     

Synthetic oligodeoxyribonucleotides showing abnormal mobilities on polyacrylamide gel electrophoresis

We found that synthetic DNA fragments containing a GCGAAAGC sequence showed higher mobilities than oligonucleotides without the sequence on denaturing polyacrylamide gel electrophoresis. For example, the fragment, GCGAAAGCT (9mer), showed higher mobility than the corresponding 8mer (CGAAAGCT). In addition, on Maxam-Gilbert sequencing, a 21mer containing the GCGAAAGC sequence showed an abnormal pattern, which were similar to those due to compression observed on sequencing of DNAs with high GC contents, as recently reported. It was suggested that this compression was due to the increased mobilities of the specific fragments with the GCGAAAGC sequence and that these fragments took on abnormal conformations.     

Factors determining vegetation recovery after abandonment of coal-mining villages

Landscape and Ecological Engineering - There have been many earlier studies of the biodiversity and ecosystem services of abandoned farmlands, but studies of abandoned villages are limited,...     

Hominid Footprints in Recent Volcanic Ash: New Interpretations from Hawaii Volcanoes National Park

Recent archeological research at Hawaii Volcanoes National Park indicates that the story behind the imprinting of at least 1773 human footprints preserved in the Ka’u Desert ash is more complex than originally thought. Footprint impressions found in desert ash layers were previously believed to have been created by the army of the Hawaiian Chief Keoua on its way back from battle in 1790. When Kilauea is said to have erupted, apparently suffocating one group, the others made it out alive, apparently leaving their footprints in the then-wet ash, which evidently dried and hardened. These features have since been preserved, often under layers of volcanic sand. This simple explanation of an event still remembered in oral tradition, is not supported by the geologic evidence and the recent discovery of hundreds of archaeological features which indicate much more prehistoric activity in the area for at least two centuries prior to 1790. This suggests other people contributed to the footprints preserved in the desert ash.