Establishment and characterization of a new,spontaneously immortalized,pancreatic ductal cell line from the Syrian golden hamster

Spontaneously immortal pancreatic cell lines are not available. By use of a defined culture medium, such a line (TAKA-1) was established from the Syrian golden hamster. Cytological, cytogenetic, molecular biological, enzymatic and receptor patterns as well as antigenicity were studied and were compared with those of the normal hamster pancreatic ductal cells in vivo. TAKA-1 cells grew exponentially in a monolayer on collagen gel in a defined medium but did not proliferate in soft agar. Ultrastructurally, the cells closely resembled the normal hamster pancreatic ductal cells. Similarities and dissimilarities were found between the normal ductal cells and TAKA-1 cells. Similarities included the presence of cytokeratin, carbonic anhydrase and some tumor-associated antigens. However, unlike the normal ductal cells, TAKA-1 cells expressed blood group A angigen and anti-vimentin, showed affinity to selected lectins, and an abnormality of chromosome 3, which is suggested to be associated with immortality. Moreover, unlike the hamster pancreatic ductal cancer cells but like the normal hamster pancreatic ductal cells, TAKA-1 cells did not have a c-Ki-ras mutation. EGF, TGF- and secretin, but not CCK or GRP, bound to the TAKA-1 cells. TAKA-1 cells produced TGF-, and their growth was stimulated by exogenous EGF in serum-free medium. This cell line presents a suitable model for biologic and pathologic study of the hamster pancreatic ductal cells in vitro.     

Characterization of Methanosarcina mazeii TMA isolated from a paddy field soil

We isolated a methanogenic strain, designated as strain TMA (=DSM 9195), from an enrichment culture inoculated with a Japanese paddy field soil. Strain TMA was Gram positive and strictly anaerobic. Cell shape was pseudosarcina-like, and cells were nonmotile. The strain was able to use methylamines, methanol, H₂–CO₂, and acetate as substrates for methanogenesis, but did not utilize formate. The optimum temperature and optimum pH were 30–37°C and 6.5–7.5 respectively. The G+C content of the DNA was 42.1 mol %. Strain TMA had DNA-DNA hybridization values of more than 80% with Methanosarcina mazeii S-6^T (T = type strain). On the basis of phenotypic and genotypic characteristics, we identified strain TMA as M. mazeii. This is the first methylotrophic methanogen isolated from a paddy field soil and identified to the species level.     

Bsr-REMI: An improved method for gene tagging using a new vector inDictyostelium

Using a plasmid pBsr2 which carries a blasticidin S-resistant gene, we have improved the method of REMI (restriction enzyme-mediated integration) provided for insertional mutagenesis inDictyostelium discoideum (bsr-REMI). To confirm usefulness of thebsr-REMI, transformation efficiency, copy number of integrated DNA, and randomness of integration into genome were examined.     

Localization ofd-amino acid oxidase mRNA in the mouse kidney and the effect of testosterone treatment

d-Amino acid oxidase (DAO), which catalyzes oxidative deamination ofd-amino acids, is known to be highly expressed in the kidney. This study was designed to examine the localization of DAO mRNA in the mouse kidney using in situ hybridization histochemistry (ISH). For comparison, ISH for mRNA of ornithine decarboxylase (ODC), which is also highly expressed in the mouse kidney, was simultaneously performed. Adult, male mice which received 1 mg of testosterone propionate or vehicle injection, were sacrificed 14 h after injection and their kidneys were removed and processed for ISH. Hybridization signals for both mRNAs were exclusively located over the epithelial cells of the proximal tubule in the vehicle-treated animals. Signals for the DAO mRNA were observed at nearly the same hybridization intensity throughout the proximal tubule, whereas hybridization signals for the ODC mRNA were observed exclusively in the pars convoluta. Following testosterone treatment, ODC mRNA in the pars convoluta was expressed with a stronger intensity than that in the vehicle-injected animals. ODC mRNA was also expressed in the pars recta with a weaker intensity than in the pars convoluta. On the other hand, DAO mRNA expression was little affected by testosterone treatment. These results indicate that, although both genes are possibly expressed in the same cells, the expression of these genes is regulated by different mechanisms.     

Chronic ethanol administration decreases fatty acyl-CoA desaturase activities in rat liver microsomes

The Δ⁹-desaturase system in liver microsome from rats treated chronically with ethanol was studied. Stearoyl-CoA desaturase activity decreased by 80% and palmitoyl-CoA desaturase activity was not detectable in microsomes from ethanol-fed rats, while activities of electron transport components such as NADH-cytochrome c and NADH-ferricyanide reductases remained unchanged. However, chronic ethanol administration resulted in an adaptive induction of the activity of NADPH-cytochrome c reductase and the contents of cytochrome b₅ and P-450. The activity of the terminal component (cyanide-sensitive factor; CSF) of the desaturase system was greatly depressed by ethanol treatment. The NADH/NAD ratio in microsomes of ethanol-fed rats increased over 2-fold. These results suggest that, during chronic ethanol ingestion, decreased activities of Δ⁹-desaturases are due mainly to a decreased content of the terminal component of the desaturase system.     

Stimulation of prolyl hydroxylase activity by chelating agents.

The activity of purified prolyl hydroxylase was enhanced several fold by addition of some chelating agents to the assay medium. Chelating agents could be classified into three groups. The chelating agents of Group I such as α, α′-dipyridyl were inactive until they reached equimolar concentration with ferrous ion in the assay mixture. The Group II agents, EDTA, diethylenetriaminepentaacetic acid, etc., stimulated the enzymatic activity 1.5- to 3-fold at equimolar concentration with ferrous ion. But the agents of both groups precipitously inhibited the enzymatic activity at concentrations greater than ferrous ion. On the other hand, Group III chelating agents, such as nitrilotriacetic acid, enhanced the enzymatic activity 5- to 10-fold at concentrations greater than ferrous ion. Nucleoside triphosphates, which also stimulate the enzymatic activity several fold and whose optimal concentrations are 1–3 × 10^?m, may be analogous to nitrilotriacetic acid of Group III.     

Pathological observation on experimental swine dysentery

Experimental swine dysentery caused by 4 cultured strains (S73/2, DJ183, DJ70 and DK762) of Treponema hyodysenteriae was studied pathologically. The distribution and quantity of treponemes were examined on tissue sections stained by the Warthin-Starry method. Of the organs the colon contained the largest number of treponemes and the cecum and rectum the second largest number. Histopathological lesions were restricted to the large intestine. They ranged from mild catarrhal colitis in the mild case to desquamative, hemorrhagic colitis in the severest case. The severity of lesion was closely associated with the quantity of treponemes present. There was no difference in quality of the lesion between any two of the strains used in this study. Electron microscope revealed a large number of free treponemes present in the intestinal lumen and crypts. Treponemes were seen more frequently in the cytoplasm of goblet cells than in that of intestinal epithelial cells. They were also observed in desquamated degenerative epithelia. A small number of them were found in intact epithelia. Morphologically, the treponeme had a granular protoplasmic cylinder at the center which was surrounded by a thin envelope. Between the cylinder and the envelope there were axial fibrils.