Two forms of secreted and thermostable luciferases from the marine copepod crustacean, Metridia pacifica

We cloned two forms of the secreted and thermostable luciferase genes, MpLuc1 and MpLuc2, from the marine copepod, Metridia pacifica. The 840-bp MpLuc1 cDNA comprised a 630-bp open reading frame encoding a 210-amino acid polypeptide (22.7 kDa). MpLuc1 had the closest homology with Metridia longa luciferase. The 753-bp MpLuc2 cDNA consisted of a 567-bp open reading frame (20.3 kDa), and it had the closest homology with Gaussia princeps luciferase. Single-specimen genomic PCR confirmed the presence of two luciferase genes in M. pacifica, and single-specimen RT-PCR revealed that both luciferase mRNAs were expressed. Both MpLuc1 and MpLuc2 (MpLucs) specifically reacted with the substrate coelenterazine producing identical bioluminescent spectra (lambdamax, 485 nm), but with different kinetics. Adding salt such as MgCl2 and CaCl2 to the reaction mixture significantly enhanced MpLuc1 and MpLuc2 activities. Wild-type MpLucs were remarkably thermostable; MpLuc1 retained about 60% of the original activity even after incubation at 90 degrees C for 30 min. MpLucs expressed in NIH-3T3 and HeLa cells were largely secreted into the culture medium. Continuous monitoring of secreted MpLuc1 driven by the c-fos promoter demonstrated the potential usefulness of MpLuc1 in nondisruptive reporter assays.     

Regulation of the formate dehydrogenase gene, FDH1, in the methylotrophic yeast Candida boidinii and growth characteristics of an FDH1-disrupted strain on methanol, methylamine, and choline.

The structural gene (FDH1) coding for NAD(+)-dependent formate dehydrogenase (FDH) was cloned from a genomic library of Candida boidinii, and the FDH1 gene was disrupted in the C. boidinii genome (fdh1 delta) by one-step gene disruption. In a batch culture experiment, although the fdh1 delta strain was still able to grow on methanol, its growth was greatly inhibited and a toxic level of formate was detected in the medium. In a methanol-limited chemostat culture at a low dilution rate (0.03 to 0.05 h[-1]), formate was not detected in the culture medium of the fdh1 delta strain; however, the fdh1 delta strain showed only one-fourth of the growth yield of the wild-type strain. Expression of FDH1 was found to be induced by choline or methylamine (used as a nitrogen source), as well as by methanol (used as a carbon source). Induction of FDH1 was not repressed in the presence of glucose when cells were grown on methylamine, choline, or formate, and expression of FDH1 was shown to be regulated at the mRNA level. Growth on methylamine or choline as a nitrogen source in a batch culture was compared between the wild type and the fdh1 delta mutant. Although the growth of the fdh1 delta mutant was impaired and the level of formate was higher in the fdh1 delta mutant than in the wild-type strain, the growth defect caused by FDH1 gene disruption was small and less severe than that caused by growth on methanol. As judged from these results, the main physiological role of FDH with all of the FDH1-inducing growth substrates seems to be detoxification of formate, and during growth on methanol, FDH seems to contribute significantly to the energy yield.     

Developmental expression profiles of axon guidance signaling and the immune system in the marmoset cortex: Potential molecular mechanisms of pruning of dendritic spines during primate synapse formation in late infancy and prepuberty (I)

The synapse number and the related dendritic spine number in the cerebral cortex of primates shows a rapid increase after birth. Depending on the brain region and species, the number of synapses reaches a peak before adulthood, and pruning takes place after this peak (overshoot-type synaptic formation). Human mental disorders, such as autism and schizophrenia, are hypothesized to be a result of either too weak or excessive pruning after the peak is reached. Thus, it is important to study the molecular mechanisms underlying overshoot-type synaptic formation, particularly the pruning phase.     

Role of conserved histidine residues in D-aminoacylase from Alcaligenes xylosoxydans subsp. xylosoxydans A-6

D-Aminoacylase from Alcaligenes xylosoxydans subsp. xylosoxydans A-6 (Alcaligenes A-6) was strongly inactivated by diethylpyrocarbonate (DEPC). An H67N mutant was barely active, with a kcat/Km 6.3 x 10(4) times lower than that of the recombinant wild-type enzyme, while the H67I mutant lost detectable activity. The H67N mutant had almost constant Km, but greatly decreased kcat. These results suggested that His67 is essential to the catalytic event. Both H69N and H69I mutants were overproduced in the insoluble fraction. The kcat/Km of H250N mutant was reduced by a factor of 2.5 x 10(4)-fold as compared with the wild-type enzyme. No significant difference between H251N mutant and wild-type enzymes in the Km and kcat was found. The Zn content of H250N mutant was nearly half of that of wild-type enzyme. These results suggest that the His250 residue might be essential to catalysis via Zn binding.     

Production of 2-phenylethanol in roses as the dominant floral scent compound from L-phenylalanine by two key enzymes, a PLP-dependent decarboxylase and a phenylacetaldehyde reductase

We investigated the biosynthetic pathway for 2-phenylethanol, the dominant floral scent compound in roses, using enzyme assays. L-[(2)H8] Phenylalanine was converted to [(2)H8] phenylacetaldehyde and [(2)H8]-2-phenylethanol by two enzymes derived from the flower petals of R. 'Hoh-Jun,' these being identified as pyridoxal-5'-phosphate-dependent L-aromatic amino acid decarboxylase (AADC) and phenylacetaldehyde reductase (PAR). The activity of rose petal AADC to yield phenylacetaldehyde was nine times higher toward L-phenylalanine than toward its D-isomer, and this conversion was not inhibited by iproniazid, a specific inhibitor of monoamine oxidase. Under aerobic conditions, rose petal AADC stoichiometrically produced NH3 together with phenylacetaldehyde during the course of decarboxylation and oxidation, followed by the hydrolysis of L-phenylalanine. Phenylacetaldehyde was subsequently converted to 2-phenylethanol by the action of PAR. PAR showed specificity toward several volatile aldehydes.     

Factor in urinary extracts from pregnant women that inhibit mouse oocyte maturation in vitro

Mouse oocyte maturation inhibitory factors, on the basis of inhibitory activity of spontaneous germinal vesicle breakdown (GVBD) of denuded mouse oocytes in culture, were extracted and partially purified by reversed-phase resin adsorption and Sephadex G-100 and G-50 column chromatographies from the urine of pregnant women. Denuded oocytes obtained from ovaries of ICR mice underwent spontaneous GVBD by cultivation for 3 h in modified Krebs–Ringer's buffered solution, while this spontaneous GVBD was found to be inhibited by adding the final preparation (U-D-4) of urine. The inhibition was dose dependent, ranging from 0.6 to 10 μg protein/ml medium. Oocytes treated with U-D-4 and resuspended in control medium resumed GVBD. The molecular mass of U-D-4 was estimated to be less than 2,000 Da with gel filtration. Ether treatment failed to extract inhibitory factor(s) from U-D-4 and pepsin treatment inactivated U-D-4, indicating that inhibitory factor(s) in U-D-4 are peptide-like substances. The inhibitory effect of U-D-4 on spontaneous GVBD was partially reversed in the presence of naloxone, a potent opioid antagonist. U-D-4s obtained from urine samples of pregnant women, nonpregnant women, and men showed the inhibitory effect on spontaneous GVBD; however, the activity of U-D-4 obtained from pregnancy urine was significantly more potent than those of the other urine samples. © 1993 Wiley-Liss, Inc.     

Postglacial environmental change of the Pacific Ocean off the coasts of central Japan

Downcore changes in microfossil assemblages and oxygen isotope ratios in three piston cores recovered from the Northwestern Pacific, off central Japan, show that the subtropical Kuroshio front was located to the south of C-4 core site (Lat. 33° N) during the last glacial. The front then advanced northward, passing over the C-4 site and the C-6 site (34.6° N) at about 13 ka and 10 ka, respectively, and reached the C-1 core site (36° N) at about 7 ka. After 5.5 ka it retreated to the area between the C-1 and C-6 sites. A brief but significant cold event, the readvance of the cold Oyashio Current, is recognized between 11 and 10 ka in the two northern cores, but the current did not reach the southern C-4 site. A contemporaneous cold event is known in the North Atlantic, and the cooling was probably a global phenomenon likely to be associated with lowering of sea level. Contamination of isotopically light water is apparent between 14 and 11 ka in the marked change in isotopic composition of benthic foraminifers. Oxygen isotope ratios of planktonic foraminifers show that prior to the advance of the Kuroshio front, the surface water at these core sites was isotopically lighter than the Kuroshio water at that time.