Induction of cell cycle progression by adenovirus E1A gene 13S- and 12S-mRNA products in quiescent rat cells.

Rat 3Y1 cell lines that express either adenovirus type 12 E1A 13S mRNA or 12S mRNA in response to dexamethasone treatment were established by introduction of recombinant vector DNA containing the E1A 13S- or 12S-mRNA cDNA placed downstream of the hormone-inducible promoter of mouse mammary tumor virus. These cell lines were growth arrested, and the induction of cell cycle progression was analyzed by flow cytometry after switch on of the cDNA by the addition of dexamethasone. The results indicate that the 13S- or 12S-mRNA product alone has the ability to cause progression of the cell cycle at a similar rate. The simultaneous addition of epidermal growth factor accelerated the rate of cell cycle progression in the transition from the G0/G1 phase to the S phase.     

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.     

Lack of association and linkage between HLA and familial polyposis coli

Summary We investigated possible association of and linkage between HLA and familial polyposis coli (FPC). In 182 individuals from 66 pedigrees of FPC and 108 individuals from a normal population, HLA-A,-B, and-C antigens were determined. When the frequencies of HLA antigens in 66 unrelated patients and in normal controls were compared, no association of FPC with HLA was observed. For the linkage analysis, HLA haplotypes of 17 affected sib pairs were investigated by the affected sib pair method. The number of pairs which shared two, one, and no haplotypes identical by descent was not significantly different from the number expected with random occurrence (P>0.95). Finally, seven families were analyzed using Morton's sequential test. A maximum lod score of-0.056 at a recombination fraction of 0.4, and a lod of-3.089 at a recombination fraction of 0.05 were obtained. Therefore, there is neither an association of nor linkage between FPC and HLA.     

Endogenous beta-galactoside-binding lectin expression is suppressed in retinol-induced mucous metaplasia of chick embryonic epidermis

The fate of endogenous beta-galactoside-binding lectin of chick embryo (14K type) was investigated during the course of skin differentiation. Lectin (14K) was found in keratinized epidermis and was localized mainly in the basal and intermediate cells. However, the protein lectin in the epidermis disappeared when the cultured skin was treated with vitamin A and mucous metaplasia was observed. The synthesis of lectin mRNA was also strongly suppressed by vitamin A in a concentration-dependent manner. On the other hand, in the dermis, in which the lectin was localized in the extracellular matrix, lectin expression was scarcely affected by vitamin A. These results indicated that the lectin was expressed in the keratinized epidermis but that its expression was suppressed in vitamin A-induced mucous-secreting epithelium. The suppression may be a result of a transition of the epidermal regulatory system to one of mucous-secreting epithelium. This is the first finding that 14K lectin expression might be regulated during the course of the epidermal differentiation.     

Cloning of the Membrane-Bound Aldehyde Dehydrogenase Gene of Acetobacter polyoxogenes and Improvement of Acetic Acid Production by Use of the Cloned Gene

A genomic clone bank of Acetobacter polyoxogenes NBI1028 constructed in Escherichia coli by use of the expression vector pUC18 was screened with antibody raised against membrane-bound aldehyde dehydrogenase (ALDH; 75 kilodaltons [kDa]) from A. polyoxogenes NBI1028. A clone that synthesized a 41-kDa protein cross-reactive with anti-ALDH antibody was isolated. For cloning of the full-length ALDH structural gene, a cosmid gene bank was screened by Southern blot hybridization with the cloned DNA as a probe, and subcloning from the positive cosmid clone was performed with shuttle vector pMV24. Plasmid pAL25, containing the full-length ALDH structural gene, was isolated and expressed in both E. coli and Acetobacter aceti to produce a fused protein (78 kDa) with a short NH₂-terminal β-galactosidase peptide. pAL25 conferred ALDH production on a mutant of A. aceti lacking the enzyme activity. Transformation of A. aceti subsp. xylinum NBI2099 with pAL25 caused 2- and 1.4-fold increases in the production rate and in the maximum concentration of acetic acid in submerged fermentation, respectively.     

Demonstration of GTP-binding proteins and ADP-ribosylated proteins in rat liver Golgi fraction

A Golgi-rich fraction isolated from rat liver was found to contain GTP-binding proteins with 20-25 kDa, which were tightly bound to the Golgi membrane. The Golgi fraction also contained two species of proteins which were ADP-ribosylated by bacterial toxins. Protein(s) which was ADP-ribosylated by botulinum toxin had a similar molecular mass as those with GTP-binding activity but was easily released from the membrane. Another protein with 46 kDa which was ADP-ribosylated by pertussis toxin was tightly bound to the membrane but had no significant GTP-binding activity under conditions tested here. These proteins were much less or negligible in the plasma membrane and the endoplasmic reticulum.     

Proalbumin is processed to serum albumin in COS-1 cells transfected with cDNA for rat albumin

Synthesis and processing of rat albumin were investigated in COS-1 cells transiently expressing rat albumin. Analysis using isoelectric focusing revealed that serum-type albumin, which is indistinguishable from the counterpart isolated from rat hepatocyte cuture medium, was secreted from the transfected COS-1 cells, indicating that proalbumin is effectively converted into serum albumin in the COS-1 cells, if not completely. Furthermore methylamine was found to cause the diminution of serum albumin released from the cells, substantiating that the proteolytical conversion of proalbumin occurs in the Golgi complex before discharge from the COS-1 cells.     

Effect of cell cholesterol content on apolipoprotein B secretion and LDL receptor activity in the human hepatoma cell line, HepG2

Human hepatoma HepG2 cells were used to study the effects of cholesterol loading and depletion on apolipoprotein B (apoB) secretion and low-density lipoprotein (LDL) receptor activity. Exposure of HepG2 cells to cholesterol and oleic acid, which elevated intracellular cholesterol levels, stimulated apoB secretion and reduced receptor-mediated uptake of LDL, whereas recombinant complexes of apolipoprotein A-I with dimyristoylphosphatidylcholine, which depleted the cellular cholesterol pool, inhibited apoB secretion and up-regulated LDL receptors. Significant negative correlation (r = -0.92, P less than 0.001) between the levels of apoB secretion and LDL uptake was found. These data suggest that the cholesterol content of the cells may induce concomitant changes in apoB secretion and LDL receptor activity.     

Studies on the structure and stabilizing factor of the CUUCGG hairpin RNA using chemically synthesized oligonucleotides.

A tridecaribonucleotide, r-UGAGCUUCGGCUC, and two analogues r(UGAGC)d(UUCG)r(GCUC) and r-UGAGCUUCIGCUC, which form a hairpin structure with a four-base-paired stem and a UUCG loop, were synthesized by the solid-phase phosphoramidite method. Properties of these three oligomers and d-TGAGCTTCGGCTC, the DNA analogue, were studied by UV, CD and NMR spectroscopy. The melting temperature (Tm) data suggest that the 2'-hydroxy1 groups and the 2-amino group of guanosine in the loop (9G) stabilize the CUUCGG hairpin which is known to have an unusually high Tm. NMR studies show that this 9G takes a syn conformation and the phosphodiester backbone has a turn at 9G-10G which is a junction of the stem and loop.