High-level expression of human acidic fibroblast growth factor and basic fibroblast growth factor in silkworm (Bombyx mori L.) using recombinant baculovirus

A hybrid of Autographa californica nuclear polyhedrosis virus and Bombyx mori nuclear polyhedrosis virus, which is infectious to both Spodoptera frugiperda and Bombyx mori, was prepared in our previous study. Two recombinant hybrid baculoviruses, carrying cDNAs of human acidic and basic fibroblast growth factors, respectively, were successfully constructed in this study, for the large-scale production of human aFGF and bFGF using silkworm as host. These recombinant viruses were used to inoculate silkworm larvae. After the infection, the recombinant proteins were not found in the hemolymph. Such nonsecretion from cells has also been observed in the established insect cell lines, Sf21 and Tn-5. Tissue distribution analysis indicated that the expressed products were mainly located in fat body and the production of the recombinant aFGF and bFGF was maximal at around 80 h postinfection. Therefore, silkworm larvae infected with recombinant viruses were dissected and fat bodies were collected for the purification of recombinant aFGF and bFGF. The expression levels in both cases were estimated to be as high as approximately 600-700 microg per larva. Furthermore, the recombinant proteins were characterized and their biological activities were evaluated by in vitro bioassay using cell culture.

Identification and characterization of genes encoding carbazole 1,9a-dioxygenase in Pseudomonas sp. strain CA10

Nucleotide sequence analysis of the flanking regions of the carBC genes of Pseudomonas sp. strain CA10 revealed that there were two open reading frames (ORFs) ORF4 and ORF5, in the upstream region of carBC. Similarly, three ORFs, ORF6 to ORF8, were found in the downstream region of carBC. The deduced amino acid sequences of ORF6 and ORF8 showed homologies with ferredoxin and ferredoxin reductase components of bacterial multicomponent dioxygenase systems, respectively. ORF4 and ORF5 had the same sequence and were tandemly linked. Their deduced amino acid sequences showed about 30% homology with large (alpha) subunits of other terminal oxygenase components. Functional analysis using resting cells harboring the deleted plasmids revealed that the products of ORF4 and -5, ORF6, and ORF8 were terminal dioxygenase, ferredoxin, and ferredoxin reductase, respectively, of carbazole 1,9a-dioxygenase (CARDO), which attacks the angular position adjacent to the nitrogen atom of carbazole, and that the product of ORF7 is not indispensable for CARDO activity. Based on the results, ORF4, ORF5, ORF6, and ORF8 were designated carAa, carAa, carAc, and carAd, respectively. The products of carAa, carAd, and ORF7 were shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis to be polypeptides with molecular masses of 43, 36, and 11 kDa, respectively. However, the product of carAc was not detected in Escherichia coli. CARDO has the ability to oxidize a wide variety of polyaromatic compounds, including dibenzo-p-dioxin, dibenzofuran, biphenyl, and polycyclic aromatic hydrocarbons such as naphthalene and phenanthrene. Since 2,2',3-trihydroxydiphenyl ether and 2,2',3-trihydroxybiphenyl were identified as metabolites of dibenzo-p-dioxin and dibenzofuran, respectively, it was considered that CARDO attacked at the angular position adjacent to the oxygen atom of dibenzo-p-dioxin and dibenzofuran as in the case with carbazole.

Cloning of genes involved in carbazole degradation of Pseudomonas sp. strain CA10: nucleotide sequences of genes and characterization of meta-cleavage enzymes and hydrolase

The DNA fragment encoding meta-cleavage enzymes and the meta-cleavage compound hydrolase, involved in carbazole degradation, was cloned from the carbazole-utilizing bacterium Pseudomonas sp. strain CA10. DNA sequence analysis of this 2.6-kb SmaI-SphI fragment revealed that there were three open reading frames (ORF1, ORF2, and ORF3, in this gene order). ORF1 and ORF2 were indispensable for meta-cleavage activity for 2'-aminobiphenyl-2,3-diol and its easily available analog, 2,3-dihydroxybiphenyl, and were designated carBa and carBb, respectively. The alignment of CarBb with other meta-cleavage enzymes indicated that CarBb may have a non-heme iron cofactor coordinating site. On the basis of the phylogenetic tree, CarBb was classified as a member of the protocatechuate 4,5-dioxygenase family. This unique extradiol dioxygenase, CarB, had significantly higher affinity and about 20-times-higher meta-cleavage activity for 2,3-dihydroxybiphenyl than for catechol derivatives. The putative polypeptide encoded by ORF3 was homologous with meta-cleavage compound hydrolases in other bacteria, and ORF3 was designated carC. The hydrolase activity of CarC for 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoic acid, the meta-cleavage compound of 2,3-dihydroxybiphenyl, was 40 times higher than that for 2-hydroxy-6-oxohepta-2,4-dienoic acid, the meta-cleavage compound of 3-methylcatechol. Alignment analysis and the phylogenetic tree indicate that CarC has greatest homologies with hydrolases involved in the monoaromatic compound degradation pathway. These results suggest the possibility that CarC is a novel type of hydrolase.

Simple method for quantifying disorientation of myofiber in endomyocardial biopsy specimens using an image analyzer

The disarray of cardiac myofibers was morphometrically evaluated in biopsy specimens, obtained from patients with hypertrophic cardiomyopathy (HCM), hypertensive heart disease (HHD), chronic phase myocarditis and controls. Microphotographs of myocardium were taken at a final magnification of x 250. For each segment of myofibers, the longitudinal direction was traced on a transparent sheet, and the angle of the traced direction to the baseline was measured by an image analyzer. The standard deviation of the angles was used as an indicator of myofiber disarray. The histograms showed a narrow variation in the control group, but a wide variation in the patients with HCM, HHD and chronic phase myocarditis. The mean value of standard deviations of myofiber angles in HCM was significantly larger than that in the other groups. In HCM, the standard deviation of the myofiber angle proved to correlate positively with IVST/LVPWT (the thickness ratio of interventricular septum to the left ventricular posterior wall) (r = 0.70, p < 0.05), and also with LVEDP (left ventricular end-diastolic pressure) (r = 0.66, p < 0.05). In conclusion, the image analyzer serves as a simple and useful tool in quantifying the disorientation of myofibers and estimating the correlation between the histological and clinical findings.

Induction of cutaneous mast cell tumors by N-methyl-N'-nitro-N-nitrosoguanidine followed by TPA in female mice of 4 out of 5 strains tested

Appreciable yields of cutaneous mast cell tumors were induced in a two-stage skin carcinogenesis protocol comprising N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) initiation followed by 12-O-tetradecanoylphorbol-13-acetate (TPA) promotion in 4 of 5 strains of mice. Only female mice of each of the 5 strains were studied. The incidences of benign and/or malignant lesions differed considerably between strains; 27% in DBA/2, 22% in BDF1, 11% in BALB/c, 10% in CDF1 and 0% in C57BL/6 mice and no mast cell tumors were detected in any of the strains when treated with the initiator alone. First found in a DBA/2 mouse at week 50, most tumors were observed after 100 weeks of promotion, and were usually small in size (less than 2 mm in diameter) and predominantly located within the corium, although they occasionally extended into the subcutaneous tissue. Histologically, the benign mast cell tumors were composed of non-encapsulated, well circumscribed densely packed sheets of discrete cuboidal or rhomboid cells. Metachromatic granules were clearly visible in the cytoplasm by Toluidine Blue staining. Two of the tumors induced in DBA/2 mice were diagnosed as malignant mast cell tumors on the twin bases of cellular atypia and deep infiltration into the muscular layer. The cutaneous mast cell tumors were constantly accompanied by subepidermal mast cell aggregations which were also commonly observed in tumor-free skin of mice receiving the initiation-promotion procedure.

Intracellular compartmentalization of fura-2 dye demonstrated by laser-excitation fluorescence microscopy: a problem in measuring cytosolic free calcium concentration using fura-2 fluorescence in vascular smooth muscle cells

Recently, we have developed a novel laser-excitation fluorescence microscope system to study intracellular calcium (Ca2+) in individual cultured vascular smooth muscle (VSM) cells using fluorescent indicators for (Ca2+). In the course of our study, it was shown that the subcellular fluorescence distribution of fura-2 was not homogeneous in VSM cells incubated with the acetoxy-methyl ester form of fura-2, fura-2/AM. The fluorescence appeared spotty or filamentous and resembled in shapes the intracellular organelles, suggesting that there was fura-2 dye compartmentalization in the organelles. To clarify the nature of the subcellular fluorescence, the soluble fraction of cells loaded with the dye was analyzed through high performance liquid chromatography (HPLC). We also examined the excitation spectra of fluorescence in the soluble fraction, which was compared with that in the cell suspension. Using HPLC, it has been shown that no other than fura-2 was found in the soluble fraction, whereas analyses of excitation spectra have indicated that the membrane fraction contained fura-2/AM or its lipophilic metabolite. On the other hand, indo-1 dye fluorescence showed a diffuse intracellular distribution, but the nuclear region had higher or sometimes lower fluorescence levels than the cytoplasm. The present results suggest that it may be necessary to assess subcellular fura-2 compartmentalization and possible interference by fura-2 AM or its lipophilic metabolite for the accurate measurement of intracellular Ca2+ concentration in VSM cells. It is also suggested that indo-1 may be more suitable for estimating Ca2+ concentration than fura-2 in individual VSM cells.

Secretory regulation of endocrine pancreas: Cyclic AMP and glucagon secretion

Activation of adrenergic beta receptors has been found to stimulate insulin release in vitro that may be mediated through the augmentation of cyclic AMP in the beta cell. The activation of adrenergic alpha receptors in the beta cell inhibits the insulin release. The present studies have shown that isoproterenol (0.62 mug/ml) and sodium dibutyryl cyclic AMP (50 mug/ml) stimulate the insulin secretion and inhibit the glucagon secretion in the presence of 50 mg/100 ml glucose by the isolated pancreatic perfusion of the rat, while norepinephrine (0.5 mug/ml) inhibits the insulin secretion induced by 150 mg/100 ml glucose and stimulates the glucaton secretion. Theophylline (50 mug/ml) does not stimulate the insulin and the glucagon secretion. When norepinephrine is added to theophylline, the output of glucagon does not occur. From these results it can be deduced that the pancreatic alpha cell function may be inhibited by elevation of intracellular cyclic AMP, in contrast to the beta cell function which is stimulated by an increment of cyclic AMP.